Patient interface systems

ABSTRACT

A headgear for positioning a patient interface structure for delivering a pressurized flow of breathable gas to the airways of a patient includes at least one flexible strap loop which is attachable to the patient interface structure by a forked region of the at least one strap loop that is mountable on the patient interface structure. The at least one strap loop positions the patient interface structure on the face of the patient. The forked region includes two forks adapted to be attached to an upper and lower portion on the patient interface structure. The two forks are connected by a bridge so that the forked region is divided into a first region and a second region, and the first region is mountable on the patient interface structure. An elbow for a patient interface system for delivering a flow of breathable gas to a patient includes a first portion having a first end configured to be connected to the patient interface system; and a second portion having a second end configured to be connected to a tube that delivers the flow of breathable gas. An outer circumferential wall includes a plurality of perpendicular steps formed therein and a plurality of vent holes are provided perpendicular to the plurality of perpendicular steps.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of International ApplicationPCT/AU2008/001557, filed Oct. 22, 2008, which claims priority toAustralian Applications 2007905737 and 2007906276, filed Oct. 22, 2007and Nov. 16, 2007, respectively, and U.S. application Ser. Nos.61/031,173 and 61/129,982, filed Feb. 25, 2008 and Aug. 4, 2008,respectively, the entire contents of each being incorporated herein byreference. This application is also a continuation-in-part of U.S.application Ser. No. 29/335,698, filed Apr. 20, 2009, the entirecontents of which are incorporated herein by reference.

FIELD OF THE INVENTIONS

The inventions relate to patient interfaces for delivery of respiratorytherapy to a patient. Examples of such therapies include ContinuousPositive Airway Pressure (CPAP), Non-Invasive Positive PressureVentilation (NIPPV), and Variable Positive Airway Pressure (VPAP). Thetherapy is used for treatment of various respiratory conditionsincluding Sleep Disordered Breathing (SDB), for example ObstructiveSleep Apnea (OSA).

BACKGROUND OF THE INVENTIONS 1. Introduction

The provision of a supply of air at positive pressure to the entrance ofa patient's airways for treatment of SDB was first disclosed in U.S.Pat. No. 4,944,310 to Sullivan. The delivery of the pressurized flow isfacilitated by a patient interface, such as a mask. Mask systems may beclassified as “nasal masks,” “full-face masks,” “nose and mouth masks”and a variety of nozzle designs, including “nasal pillows,” “nasalpuffs,” “nasal prongs” and “nasal cannulae” designs. An example of anasal pillow-type mask system is disclosed in WO 2004/073778 A1(Gunaratnam et al.), the contents of which are hereby incorporated byreference.

While different manufacturers use different terminology to refer todifferent components, patient interfaces systems, also called masksystems, typically comprise:

-   -   (i) a cushioning element    -   (ii) a headgear system to position and retain the cushioning        element in position;    -   (iii) a rigid structure, known as a frame or shell; and    -   (iv) an air delivery tube.

1.1 Cushioning Element

The cushioning element, or cushion, generally includes a soft,conforming structure made from a material such as a silicone, a gel, ora foam. In use the cushion is held against the appropriate part of theface to effect a seal. The cushioning element should form an adequateseal with the entrance to the airways in order to maintain sufficientair pressure for splinting open the airways. In some cases it may not benecessary to form a complete seal provided an adequate supply of air canbe provided at appropriate pressures and flow rates for effectivetherapy.

Nasal pillows and nasal puffs form a seal on the outside of the nares,whereas nasal prongs and nasal cannulae are positioned further into thenares and may form a seal on an inside surface of a nare, rather than anoutside surface. The location of the seal is a consideration becausedifferent surfaces have different orientations, meaning that the forcevector needed to form a seal may have a different direction. This mayresult in a headgear that is appropriate for one design beinginappropriate for another. Furthermore, different seal types may bepreferred by different patients, and may be regarded as being morecomfortable by some patients.

1.2 Headgear System

A mask system typically further comprises a range of frame and headgearsystems intended to provide force vectors of appropriate magnitude anddirection to hold the cushion in place.

1.3 Frame

Many mask systems include a rigid, or semi-rigid, structure referred toas a shell or frame. Together the cushioning element and the frame maydefine a chamber. Typically, the cushion, headgear and an air deliverytube are attached to the frame. The frame serves as an anchoring pointfor the cushion, headgear and tube. Past efforts in mask design havebeen directed towards mechanisms for anchoring the frame in a fixedposition with respect to the face and then attaching the cushion to theframe to form a seal.

1.4 Tube

Many mask systems require some form of tube, hose, or conduit to deliverthe flow of air to the mask for breathing by the patient. In use, tubedrag forces can disrupt the effectiveness of the seal. This can be theresult of the weight of the tube and/or movement of the patient. Whiletube drag can be alleviated to some extent by the use of swivels, balland socket joints, and tube anchoring arrangements, many patients feelthe need to over-tighten headgear straps in an attempt to reduce theproblem, leading to discomfort.

2 Prior Art

Design of an effective respiratory mask system requires consideration ofmany factors. Apparently subtle changes may improve or decrease comfortor effectiveness.

While millions of people suffer from the condition of sleep disorderedbreathing, many fail to comply with therapy because of problems withcomfort, ease of use, stability, leak, and obtrusiveness, and thusexpose themselves to health risks.

Some prior art mask systems attempt to anchor a rigid frame in a fixedposition with respect to the face and require patients to increaseheadgear tension to a level sufficiently high to overcome the sealdisruptive effects of patient movement, and/or tube drag.

Whilst some smaller patient interfaces (such as some nasal puffs, andsome nasal prongs) may be less obtrusive than larger masks (such as afull-face mask) they can suffer from a lack of stability. Interfacestability of such smaller interfaces was improved by holding the framein a fixed position in front and below the patient's nares. The cushion,including the nozzles, extends from this frame to the nares. The framewas held in a rigid fashion (i.e. a set location) aiming to ensurecorrect alignment of the pillows.

Some prior art patient interfaces included swivel elbows orball-and-socket joints.

Some headgear designs incorporated semi-rigid elements that increasedstability of the mask frame. Some frames were designed having ahorizontally central tube attachment point.

Some prior patient interfaces have required patients to increaseheadgear tension forces to a high level in an attempt to overcomedisruptive forces. This can lead to excessive forces on sensitiveregions of the face, resulting in discomfort to the patient.

Referring to FIG. 1, a prior art respiratory mask system may include acushion 24 comprising, for example, nasal pillows. The cushion 24 issupported on a rigid frame or shell 18 and a flexible component 22, forexample a gusset, is provided between the cushion 24 and the frame 18.An air delivery hose or tube 16 is connected to the frame 18 for thedelivery of the flow of pressurized breathable gas. A rigid headgear 20is connected to the frame 18 to maintain the cushion 24 in sealingcontact with the nose of the patient 1.

Cushions which may be used in such a prior art respiratory mask systemas shown in FIG. 1 include those disclosed, for example, in ResMedLtd.'s Swift® LT.

FIG. 2 schematically illustrates another respiratory mask systemaccording to the prior art, the Fisher & Paykel Infinity® 481 mask. Acushion 24 comprising nasal prongs 23 is attached to a mask frame orshell 18. The mask frame includes headgear connectors 26 provided onsides of the mask frame 18. A vent including a plurality of vent holes28 is also provided in the mask frame 18.

The mask frame 18 is connected to an air delivery hose or tube 16 by aswivel elbow 17. The air delivery tube 16 is connected to a flow ofpressurized breathable gas, such as generated by a blower or flowgenerator, by a coupling element 30.

As the headgear is connected to the mask frame 18 by the headgearconnectors 26, any relative movement between the mask frame 18 and thepatient's face may result in a disruption of any seal that may haveformed.

SUMMARY OF THE INVENTION

One aspect relates to providing comfortable, stable, effective,unobtrusive patient interface systems for delivering a supply of air atpositive pressure to the entrance of a patient's airways. Another aspectrelates to a patient interface system that fits a wide range ofpatients, has improved manufacturability and improved ease-of-use.

Another aspect relates to providing patient interface systems whereforces applied to the patient interface structure, such as from tubedrag forces or movement of the patient, does not disrupt the sealbetween the patient interface structure and the patient's airways.

Yet another aspect relates to providing patient interface systems wherethe patient interface structure, which includes a seal, and a sealpositioning and stabilizing structure are coupled to the patient and theair delivery tube is decoupled from the seal. Another aspect is thatforces on an air delivery tube and elbow are decoupled from pillows andheadgear.

A further aspect relates to patient interface systems in which tensionof the seal positioning and stabilizing structure may be set with alesser regard to overcoming tube drag as the effects of tube drag areisolated from disrupting the seal via decoupling. Thus in accordancewith this aspect, the tension of the seal positioning and stabilizingstructure may be reduced and patient comfort increased.

Still another aspect relates to providing patient interface systems inwhich the patient interface structure is connected to a swivel elbowassembly without the use of a rigid frame or shell.

Another aspect of the present technology is a conforming patientinterface structure that reduces the number of, or does not include,rigid components. For example, in one form the patient interface doesnot include a rigid frame.

Another aspect of the present technology is a patient interfacestructure that in use flexibly wraps around an underside of a patient'snose and accommodates different alar angles.

Another aspect of the present technology is a patient interfacestructure that accommodates movement of an air delivery tube whilstmaintaining an effective seal.

Another aspect of the present technology is a stabilizing structure thatdirects a seal effecting force to a region close to the sealing surface,e.g. the base of the nose. A force close to the sealing surface reducesa bending arm.

According to yet another aspect of the technology, a front portion of aseal positioning and stabilizing structure is molded from a flexiblepolymer, for example silicone. Preferably, the seal positioning andstabilizing structure does not include hard plastic stabilizers.

According to a sample embodiment, a patient interface system fordelivery of a supply of air at positive pressure to the entrance of apatient's airways for treatment of sleep disordered breathing comprisesan air delivery tube connected to a flexible portion of a plenum; a ventstructure having sufficient rigidity to support its own weight undergravity and/or not to block or fold under tube movement or tube drag; apatient interface structure, the patient interface structure comprisinga seal forming structure arranged on a top portion of the plenum; and aseal positioning and stabilizing structure connected to a flexibleportion of the plenum, wherein the seal-forming structure issubstantially decoupled from a tube drag force.

According to another sample embodiment, a nasal pillow for delivery of asupply of air at positive pressure to the entrance of a patient'sairways for treatment of sleep disordered breathing comprises a stalk; afrusto-conical portion connected to the stalk at a base portion of thefrusto-conical portion, the frusto-conical portion comprising a springstructure at base of the frusto-conical portion configured to engage thetop lip of the patient and rotate the stalk away from the patient's toplip.

According to yet another sample embodiment, a patient interfacestructure for delivery of a supply of air at positive pressure to theentrance of a patient's airways for treatment of sleep disorderedbreathing comprises a flexible base portion; a seal-forming structureconnected to base portion; and lateral connectors connected to theflexible base portion substantially in a same plane as a base of theseal-forming structure, wherein the flexible base portion comprises aflexible side-walled plenum comprising an orifice adapted to receive thesupply of air, the orifice having an axis substantially parallel to anaxis of the seal-forming structure.

According to a further sample embodiment, a decoupling assembly fordecoupling forces applied by a tube on a patient interface structureconfigured to deliver of a supply of air at positive pressure to theentrance of a patient's airways for treatment of sleep disorderedbreathing, the patient interface structure comprising a flexible baseportion connected to a seal-forming structure, the patient interfacestructure being held in engagement with the patient in use by a sealpositioning and stabilizing structure connected to the flexible baseportion, the decoupling assembly comprising the flexible base portion,the seal-forming structure, and at least one of a portion of the sealpositioning and stabilizing structure, a swivel elbow, a ball andsocket, a swivel sealing ring, and the tube.

According to a still further sample embodiment, a seal positioning andstabilizing structure for a patient interface structure for delivery ofa supply of air at positive pressure to the entrance of a patient'sairways for treatment of sleep disordered breathing comprises a flexiblemolded strap comprising a stiffened portion.

In another aspect of the disclosure, a patient interface adapted to beconnected to an air delivery tube comprises an under-the-nose gasdelivery unit and a plurality of components operatively coupled to thegas delivery unit, said components including headgear, a plenum, frame,or base, and an elbow; and a decoupling system to decouple (oralternatively means for decoupling) at least a portion of a drag (orother dynamic force) from the air delivery tube which would otherwise beapplied to the gas delivery unit. The gas delivery unit may be in theform of nasal prongs which are inserted into the nares to form a sealwithin the wearer's nasal passages, nozzles that seal against the lower,exterior surface of the nares, or nasal cannulae (which are partlyinserted into the nasal passages but do not necessarily form a sealtherewith). The nozzles may include stalks, heads or other structure tohelp contribute to decoupling of drag or other dynamic forces. Theplurality of components may also include a sealing ring which maycontribute to decoupling of tube drag force. The decoupling system (ormeans for decoupling) may include two or more (or all) of saidcomponents (as well as the gas delivery unit itself, e.g, variousportions of nozzles) working in concert with one another to decouple theforce from the gas delivery unit.

According to yet another sample embodiment, a headgear for positioning apatient interface structure for delivering a pressurized flow ofbreathable gas to the airways of a patient comprises at least oneflexible strap loop which is attachable to the patient interfacestructure by a forked region of the at least one strap loop that ismountable on the patient interface structure, wherein the at least onestrap loop positions the patient interface structure on the face of thepatient, the forked region includes two forks adapted to be attached toan upper and lower portion on the patient interface structure, the twoforks are connected by a bridge so that the forked region is dividedinto a first region and a second region, and the first region ismountable on the patient interface structure.

According to a still further embodiment, an elbow for a patientinterface system for delivering a flow of breathable gas to a patientcomprises a first portion having a first end configured to be connectedto the patient interface system; and a second portion having a secondend configured to be connected to a tube that delivers the flow ofbreathable gas, wherein an outer circumferential wall comprises aplurality of perpendicular steps formed therein and a plurality of ventholes are provided perpendicular to the plurality of perpendicularsteps.

According to an even further embodiment, a method of manufacturing anelbow for a patient interface system for delivering a flow of breathablegas is provided. The elbow comprises a first portion having a first endconfigured to be connected to the patient interface system and a secondportion having a second end configured to be connected to a tube thatdelivers the flow of breathable gas. The method comprises forming aplurality of perpendicular steps in an outer circumferential wall of thesecond portion and forming a plurality of vent holes perpendicular tothe plurality of perpendicular steps.

Other aspects, features, and advantages will become apparent from thefollowing detailed description when taken in conjunction with theaccompanying drawings, which are a part of this disclosure and whichillustrate, by way of example, other aspects and principles.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments, wherein:

FIG. 1 schematically depicts a patient interface system according to theprior art;

FIG. 2 schematically illustrates a patient interface system according tothe prior art;

FIG. 3 a schematically depicts a patient interface system according to asample embodiment;

FIG. 3 b schematically illustrates a vector provided by sampleembodiments;

FIG. 4 schematically illustrates a patient interface structure accordingto a sample embodiment;

FIG. 5 a schematically illustrates a patient interface system accordingto another sample embodiment;

FIG. 5 b schematically illustrates a flexible elbow according to asample embodiment;

FIGS. 5 c and 5 d schematically illustrate an elbow configurationaccording to a sample embodiment;

FIG. 6 schematically illustrates a patient interface system according toanother sample embodiment;

FIG. 7 a schematically illustrates a patient interface system accordingto other sample embodiments;

FIGS. 7 b and 7 c schematically illustrate straps according to sampleembodiments;

FIG. 7 d schematically illustrates a patient interface structureaccording to a sample embodiment;

FIG. 8 a schematically illustrates a patient interface structureincluding nasal pillows in accordance with a sample embodiment;

FIG. 8 b schematically illustrates a connector of a patient interfacestructure according to a sample embodiment;

FIG. 8 c schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIG. 8 d schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIG. 8 e schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIG. 8 f schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIG. 8 g schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIG. 8 h schematically illustrates a linking element of the patientinterface structure of FIG. 8 f;

FIG. 8 i schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIG. 8 j schematically illustrates the linking element of the patientinterface structure of FIG. 8 i;

FIGS. 8 k schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIGS. 8 l and 8 m schematically illustrate a comparison between sampleembodiments;

FIG. 8 n schematically illustrates a patient interface structureincluding nasal pillows in accordance with another sample embodiment;

FIGS. 9 a and 9 b schematically illustrate a patient interface structureto elbow or frame connection in accordance with a sample embodiment;

FIG. 10 schematically depicts a patient interface system according to asample embodiment;

FIG. 11 schematically depicts a patient interface system according to asample embodiment;

FIGS. 12 a and 12 b schematically illustrate a side view and a rearview, respectively, of a patient interface system according to anothersample embodiment;

FIGS. 13 a and 13 b schematically illustrate a side view and a rearview, respectively, of a patient interface system according to anothersample embodiment;

FIGS. 14 a and 14 b schematically illustrate a side view and rear view,respectively, of a patient interface system according to another sampleembodiment;

FIGS. 15 a and 15 b schematically illustrate a side view and rear view,respectively, of a patient interface system according to another sampleembodiment;

FIGS. 16 a-16 g schematically illustrate left and right main straps of amain strap loop of a seal positioning and stabilizing structureaccording to a sample embodiment;

FIGS. 17 a-17 g schematically illustrate a sample embodiment of apatient interface structure according to sample embodiments;

FIGS. 17 h and 17 i schematically illustrate a swivel seal ringaccording to a sample embodiment in connection with a patient interfacestructure according to a sample embodiment;

FIG. 17 j schematically illustrates a patient interface system accordingto a sample embodiment including an air delivery tube, an elbow, aswivel seal ring, and a patient interface structure;

FIG. 17 k schematically illustrate a seal formed between an elbow and aswivel seal ring according to a sample embodiment;

FIG. 17 l schematically illustrates a seal ring according to anothersample embodiment;

FIG. 17 m schematically illustrates a seal ring according to anothersample embodiment;

FIGS. 17 n and 17 o schematically illustrate a swivel seal ringaccording to another sample embodiment;

FIGS. 18 a-18 c schematically illustrate a connection of the patientinterface structure to the seal positioning and stabilizing structureaccording to one sample embodiment;

FIGS. 18 d-18 q schematically illustrate a connection of the patientinterface structure to the seal positioning and stabilizing structureaccording to other sample embodiments;

FIGS. 18 r and 18 s schematically illustrate cross sections of a patientinterface structure according to a sample embodiment;

FIGS. 19 a-19 e schematically illustrate a ladder lock connectoraccording to a sample embodiment;

FIGS. 20 a and 20 b schematically illustrate a seal positioning andstabilizing structure strap connector according to a sample embodiment;

FIGS. 21 a and 21 b schematically illustrate another sample embodimentof a seal positioning and stabilizing structure strap connector;

FIGS. 22 a and 22 b schematically illustrate a sample embodiment of aseal positioning and stabilizing structure strap connector;

FIGS. 23 a-23 c schematically illustrate a seal positioning andstabilizing structure strap connector according to another sampleembodiment;

FIGS. 24 a-24 l schematically illustrate a seal positioning andstabilizing structure comprising connectors according to another sampleembodiment;

FIGS. 24 m-24 q schematically illustrate a patient interface systemaccording to a sample embodiment including the seal positioning andstabilizing structure of FIGS. 24 a-24 l;

FIG. 24 r schematically illustrates a strap connector according toanother sample embodiment;

FIGS. 25 a-25 i schematically illustrate a seal positioning andstabilizing structure comprising connectors according to another sampleembodiment;

FIGS. 26 a-26 f schematically illustrate seal positioning andstabilizing structure connectors according to other sample embodiments;

FIGS. 27 a and 27 b schematically illustrate nasal pillows according toa sample embodiment;

FIGS. 28 a and 28 b schematically illustrate a nasal pillow according toanother sample embodiment;

FIGS. 29 a and 29 b schematically illustrate a nasal pillow according toanother sample embodiment;

FIGS. 30 a and 30 b schematically illustrate a nasal pillow according toanother sample embodiment;

FIGS. 31 a and 31 b schematically illustrate a nasal pillow according toanother sample embodiment;

FIGS. 32 a and 32 b schematically illustrate a nasal pillow according toanother sample embodiment;

FIGS. 33 a-33 f schematically illustrate a nasal pillow according toanother sample embodiment;

FIGS. 34 a and 34 b schematically illustrate a nasal pillow according toanother sample embodiment;

FIG. 35 schematically illustrates nasal pillows according to anothersample embodiment;

FIG. 36 schematically illustrates a nasal pillow according to anothersample embodiment;

FIG. 37 schematically illustrates a nasal pillow according to anothersample embodiment;

FIG. 38 schematically illustrates a nasal pillow according to yetanother sample embodiment;

FIGS. 39 a and 39 b schematically illustrates a nasal pillow accordingto another sample embodiment;

FIGS. 40 a-40 h schematically illustrate nasal pillows according toother sample embodiments;

FIG. 41 schematically illustrates a nasal pillow configuration accordingto another sample embodiment;

FIG. 42 schematically illustrate a nasal pillow according to anothersample embodiment;

FIGS. 43 a-43 c schematically illustrate a patient interface systemaccording to a sample embodiment in various stages of sealing engagementwith a patient;

FIGS. 44 a-44 c schematically illustrate a patient interface systemaccording to a sample embodiment in various stages of sealing engagementwith a patient;

FIGS. 45 a and 45 b schematically illustrate a patient interface systemaccording to a sample embodiment;

FIGS. 46 a-46 e schematically illustrate a patient interface systemaccording to a sample embodiment;

FIGS. 47 a and 47 b schematically illustrate straps of seal positioningand stabilizing structures according to sample embodiments;

FIGS. 48 a and 48 b schematically illustrate a patient interface systemaccording to a sample embodiment;

FIGS. 49 and 50 schematically illustrate an elbow for a patientinterface system according to a sample embodiment;

FIG. 51 schematically illustrates a cross section of the elbow of FIGS.49 and 50;

FIG. 52 schematically illustrates a method of manufacturing the elbow ofFIGS. 49-51; and

FIG. 53 schematically illustrates an apparatus for manufacturing anelbow according to the prior art.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The following description is provided in relation to several embodimentswhich may share common characteristics and features. It is to beunderstood that one or more features of any one embodiment may becombinable with one or more features of the other embodiments. Inaddition, any single feature or combination of features in any of theembodiments may constitute additional embodiments.

In this specification, the word “comprising” is to be understood in its“open” sense, that is, in the sense of “including”, and thus not limitedto its “closed” sense, that is the sense of “consisting only of”. Acorresponding meaning is to be attributed to the corresponding words“comprise,” “comprised” and “comprises” where they appear.

The term “air” will be taken to include breathable gases, for exampleair with supplemental oxygen. It is also acknowledged that blowers orflow generators described herein may be designed to pump fluids otherthan air. The term “rigid” will be taken to mean not readily deformingto finger pressure, and/or the tensions or loads typically encounteredwhen setting up and maintaining a patient interface in sealingrelationship with an entrance to a patient's airways. The term“semi-rigid” means being sufficiently rigid to not substantially distortunder the effects of tube drag.

3 Patient Interface Systems 3.1 Introduction

FIG. 3 a schematically illustrates an aspect of the present technologywhereby headgear tension is directed close to the base of the nose andpotentially disruptive effects of tube drag are isolated or decoupledfrom the seal. See also FIG. 4. By way of contrast, refer to FIG. 1where headgear structure attempts to stabilize a frame at a point spacedfrom the sealing surface (the base of the nose) and whereby the tube isdirectly coupled to the headgear via the rigid frame. Referring to FIG.3 a, a patient interface system according to a sample embodiment maycomprise a patient interface structure 32 configured to sealingly engagethe airways of the patient 1. The patient interface structure 32 maycomprise a seal, for example, nasal pillows or nasal prongs, tosealingly engage the patient's airways. As used herein, the term “nasalpillow” refers to a nozzle-like structure that is configured to beinserted at least partly into the nasal passageway of the patient andform a seal against an outer surface of the patient's nare.

Nasal pillows in accordance with the present technology include: afrusto-cone, at least a portion of which forms a seal on an underside ofthe patient's nose; a stalk, a flexible region on the underside of thecone and connecting the cone to the stalk. In addition, the structure towhich the nasal pillow of the present technology is connected includes aflexible region adjacent the base of the stalk. The flexible regions canact in concert to facilitate a universal joint structure that isaccommodating of relative movement—both displacement and angular—of thefrusto-cone and the structure to which the nasal pillow is connected.For example, the frusto-cone may be axially displaced towards thestructure to which the stalk is connected.

A related pillow in accordance with the present technology is describedin WO 2006/130903 A1, the contents of which are hereby incorporated byreference, for example in paragraphs [00254] and [00255] and FIG. 66 c.The term “nasal prong” refers to a nozzle-like structure that isconfigured to be inserted into the patient's nasal passageway and form aseal with the interior of the patient's nasal passageway. It should alsobe appreciated that the patient interface structure 32 may comprise anasal patient interface structure or a full face patient interfacestructure, i.e. a structure configured to cover part of, or all of, thepatient's nose and/or mouth and seal against the patient's face. Thepatient interface structure may be formed of, for example, silicone,foam, or gel.

The patient interface structure 32 may be connected to an air deliveryhose or tube 16 by a decoupling arrangement 34. The decouplingarrangement 34 may include, for example, a flexible portion of thepatient interface structure 32, a swivel elbow including, e.g., a balland socket connection, and/or a swivel seal ring. The air delivery hosemay be a retractable hose, as disclosed, for example, in U.S. PatentApplication Publication 2009/0078259 A1, the entire contents of whichare incorporated herein by reference.

The patient interface system may also comprise a seal positioning andstabilizing structure 36 that is configured to position and stabilizethe patient interface structure 32 in sealing engagement with thepatient's airways. The seal positioning and stabilizing structure 36 maybe flexible. As shown in FIG. 3 a, the seal positioning and stabilizingstructure is connected to the patient interface structure 32. The sealpositioning and stabilizing structure 36 may include a side straps, ormembers, 38 configured to extend along each side of the patient's face,only one being shown in FIG. 3 a, a top strap 40 configured to extendacross the top of the patient's head, and a rear strap 42 configured toextend around the back of the patient's head.

In use, each side strap 38 of the seal positioning and stabilizingstructure 36 may be attached to the patient interface structure 32. Forexample, a connector may be provided on each side of the patientinterface structure 32, one on each side of the nose of the patient 1.It should be appreciated that multiple connectors may be provided to thepatient interface structure and in any arrangement, for example twoconnectors on each side of the nose of the patient. The pair ofconnectors form a connection between the patient interface structure 36and the seal positioning and stabilizing structure 36 as described inmore detail herein. The connection is close to the entrance to the naresof the patient 1. In this way, the straps 38, 40, 42 of the sealpositioning and stabilizing structure 36 hold the seal in positionagainst the face of the patient more directly than in prior artarrangements, such as the prior art arrangement shown in FIG. 1. In theprior art arrangement of FIG. 1, the connection of the seal positioningand stabilizing structure strap to the frame is displaced from theentrance to the patient's nares and the patient interface structure isheld against the face of the patient in an indirect manner.

In the arrangement shown in FIG. 3 a, the decoupling arrangement 34 isprovided between the connection of the straps 38 of the seal positioningand stabilizing structure 36 and the connection with the air deliverytube 16 so that tube drag does not directly impact the seal formedbetween the patient interface structure 32 and the patient's airways.

In a typical prior art arrangement, for example the one shown in FIG. 1,the tension of the headgear is often set at a level both to form a sealand to overcome tube drag that may occur. However, according to thesample embodiment shown in FIG. 3 a, the tube drag is to some extentdecoupled from the seal formed between the patient interface structure32 and the patient's airways and the tension provided by the sealpositioning and stabilizing structure need only be set at a levelnecessary for sealing. Hence, the tension may be set with a lesserregard for overcoming tube drag. The decreased tension providesincreased patient comfort.

As shown in FIG. 3 a, the flexible seal positioning and stabilizingstructure 36 may be configured so that the force vectors provided by thestraps 38, 40, 42 of the seal positioning and stabilizing structure 36maintain the patient interface structure 32 in sealing engagement withthe nares of the patient 1. It should be appreciated, however, thatother seal positioning and stabilizing structures may be utilized, asdescribed in more detail herein. For example, straps may be routedaround and engaged with the ears of the patient. According to anothersample embodiment , the straps may be eliminated and a nasal clip may beused to hold the seal of the patient interface structure 32 in position.

The seal positioning and stabilizing structure 36 may be formed of afoam and fabric laminated material, such as BREATHOPRENE®.Alternatively, the seal positioning and stabilizing structure 36 may bemade from silicone or other polymers. One of the benefits of usingsilicone or BREATHOPRENE® is there is no difference in temperature ofpatient's skin when using either silicone or BREATHOPRENE® headgear.However, silicone can discolor over time (typically oxidizes to yellow).Therefore, it may be desirable to add a tint, such as light blue, to thesilicone to reduce the visual impact of discoloration. Sharp corners ofthe headgear may also be rounded to reduce incidences of irritation tothe patient's skin.

The silicone could be polished or matte on both sides or matte on oneside and polished on the other—preferably matte on both sides, or matteon the skin contacting side and polished on the outer side. Mattesurface finish gives the perception of comfort.

The decoupling arrangement 34 acts as a flexible connection and linksthe patient interface structure 32 to the air delivery tube 16.According to the sample embodiment shown in FIG. 3 a, only the seal ofthe patient interface structure 32 is held in a set location. There isno shell or frame that needs to be held in a set location. Thedecoupling arrangement 34 is free to move with the air delivery tube 16,thereby reducing tube drag and increasing the stability of the sealformed between the patient interface structure 32 and the airways of thepatient 1.

Use of the seal positioning and stabilizing structure 36 also permitsrotation of the plane of the patient interface structure 32 with respectto the seal positioning and stabilizing structure 36 to accommodatedifferent naso-labial angles and different positions of the mask in use.For example, the connectors provided on the patient interface structure32 may include a plurality of connection points to allow the relativeposition of the patient interface structure 32 with respect to the sealpositioning and stabilizing structure 36 to be changed or adjusted. Theaxis about which rotation may be provided may be defined as beingparallel to a line drawn through both eyes of the patient, and beinglocated below the nose of the patient.

As shown in FIG. 3 b, a desirable vector 404 will produce force normalto the nares. The entire vector 404 pulls the seal, e.g. the pillows,against the nares.

The vectors of the seal positioning and stabilizing structure 36 of thesample embodiments are configured to force the seal, e.g. the pillows,up against the patient's nose. The vectors may be modified by thedirection of the straps 38, 40, 42. For example, the straps 38 mayextend higher on the face (i.e. closer to the eyes than the ears of thepatient's cheek) to increase force in the vertical axis therebyincreasing the force up and against the user's nose.

The shape of the straps 38, 40, 42 may also be configured to provide adesirable vector: According to sample embodiments, an arrangementwithout a frame requires orientation of the pillows using the sealpositioning and stabilizing structure alone. The width of the straps maybe varied to force the seal to tilt in the direction indicated by thevector 404. The width of the straps may be gradually increased from thecheek region to the nasal region to stabilize the patient interfacestructure 32.

Altering the thickness of the straps changes the rigidity and thus forcedistribution along the straps.

Referring to FIGS. 45 a and 45 b, a patient interface system accordingto a sample embodiment includes a patient interface structure 32including a flexible base 6. A seal is supported by the flexible base 6.The patient interface structure 32 is configured to be held in sealingengagement with the entrance to the patient's airways. The patientinterface structure 32 is held in sealing engagement with the patient'sface by a seal positioning and stabilizing structure 36 that includes amain strap loop 74 and a rear strap 42. The main strap loop 74 includesa right main strap 74 r and a left main strap 74 l that are configuredto be connected at respective first ends to the patient interfacestructure 32. The right and left main straps 74 r, 74 l are configuredto be connected to each other at respective second ends, for example bya connector 71, for example a buckle. A rear strap 42 of the sealpositioning and stabilizing structure 36 extends around the back of thepatient's head at a position above the patient's ears and is connectedat respective ends to the right and left main straps 74 r, 74 l atpositions between the first and second ends of the straps 74 r, 74 l.

Referring to FIGS. 48 a and 48 b, a patient interface system accordingto another sample embodiment includes a patient interface structure 320including a flexible base. A seal is supported by the flexible base. Thepatient interface structure 320 is configured to be held in sealingengagement with the entrance to the patient's airways. The patientinterface structure 320 is held in sealing engagement with the patient'sface by a seal positioning and stabilizing structure that includes amain strap loop 74 and a rear strap 85 having adjustable ends 85 e. Themain strap loop 74 includes a right main strap 74 r and a left mainstrap 74 l that are configured to be connected at respective first endsto the patient interface structure 320. The right and left main straps74 r, 74 l may be connected to each other at respective second ends, forexample by a connector, for example a buckle. The rear strap 85 of theseal positioning and stabilizing structure extends around the back ofthe patient's head at a position above the patient's ears and isconnected at respective ends to the right and left main straps 74 r, 74l at positions between the first and second ends of the straps 74 r, 74l.

The right and left main straps 74 r, 74 l may be formed, for example,from silicone. The silicone may be, for example, translucent ortransparent. The patient interface system is therefore less obtrusiveand presents a visually more appealing appearance (e.g. to a patient'sbed partner).

The “take off angle” of the straps 74 r, 74 l from a connection pointprovides a more direct angle to a base of the patient's temple and aregenerally higher up on the patient's face. The patient interfacestructure also conforms, or wraps around, the region of the patient'smouth and provides less interference with the area around the mouth. Theseal positioning and stabilizing structure also covers less of an extentof the patient's face.

3.2 Patient Interface Structure 3.2.1 Patient Interface StructureIncluding Nozzle Assembly Seal

Referring to FIG. 4, a patient interface structure 32 according to asample embodiment includes a seal 2 configured to sealingly engage thepatient's airways. The seal 2 may comprise a nozzle assembly 3 that maycomprise a pair of nasal pillows 4 connected to a base portion 6. Thepillows 4 each include a conical portion 8 at least part of which isadapted to form a seal with a nare of the patient 1. As discussed above,a portion of each pillow 4 is configured to be inserted into thepatient's nasal passageway, but not to form a seal inside the nasalpassageway. The conical portion 8 of the pillow 4 includes a sealingsurface, or zone, 8 a that is configured to engage the nare of thepatient and form a seal. The sealing surface, or zone, 8 a may be asdisclosed, for example in FIG. 21 of WO 2004/073778 A1, which isincorporated herein by reference. Each nasal pillow 4 also includes astalk, or neck portion, 10 which connects the nasal pillow 4 to aflexible base 6. The stalk, or neck portion, 10 may have a length ofbetween about 3 mm to about 6 mm.

The flexible base 6 is able to wrap around the underside of the nose inuse when under tension, and can accommodate different facial geometries.The flexible base 6 includes a pair of connectors 12 configured forconnection to a seal positioning and stabilizing structure. The sealpositioning and stabilizing structure connectors 12 are arranged at atop portion 6 t of the flexible base 6, generally in the same plane asthe base of the stalks of the nasal pillows 4. As used herein, the term“top portion” refers to the portion of the flexible base that isadjacent to the seal of the patient interface structure. When viewedfrom the side (for example in FIGS. 17 g and 17 h) an axis through thestalks of the pillows is generally parallel to a normal to the aperture324 wherethough a supply of air is delivered. This arrangementfacilitates a generally narrower patient interface structure than forexample the ResMed SWIFT® I (see for example FIG. 76A of WO 2004/073778A1), or the Innomed NASAL AIRE™ I where air is fed from the side leadingto a wider overall mask structure, and hence a patient interfacestructure in accordance with the present technology is more amenable toside-sleeping by a patient. Other patient interface structures, such asin the Fisher & Paykel OPUS™ and OPUS™ 360, include air delivery at anobtuse angle with respect to the angle of the axis of the nasal pillowwhen viewed from a corresponding orientation to FIGS. 17 g and 17 h.This approach may lead to a greater bulk of structure.

Tension 14 is applied to patient interface structure 32 by the sealpositioning and stabilizing structure to hold the nasal pillows 4 of theseal 2 in sealing engagement with the nares of the patient 1. A lowerportion 6 l of the flexible base 6 forms part of a decouplingarrangement. For example, the lower portion 6 l of the flexible base 6may comprise a gusset, such as the gusset disclosed in WO 01/97893 A1,which is incorporated herein by reference. As used herein, the term“lower portion” refers to the portion of the flexible base that isconfigured to be connected to an air delivery tube or hose, or to aframe or shell. The lower portion 6 l may define a plenum with flexibleside walls. The plenum is flexible, but not so limp or floppy that itcannot support its own weight. In other words, the plenum is capable ofholding its shape before pressurization by the flow of breathable gas.In this sense, the plenum may be described as semi-rigid.

The plenum may have flexible bellows-like structure on left- andright-hand sides, and narrowed portions adjacent the top lip andunderside of nose to avoid contact therewith in use. See for exampleFIG. 17 a where the end of line 329 is located in a flexiblebellows-like region 339 and the end of arrow 320 is adjacent a narrowedregion 321, as also shown in FIG. 18 r. See also FIG. 17 d where T4indicates a thickness suitable to provide the flexibility illustrated inFIGS. 43 a-43 c and FIGS. 44 a-44 c. The flexibility of the plenum isfacilitated by manufacture in a material such as silicone with a Shore Adurometer in the range of about 20 to about 60, more preferably about 30to about 50, most preferably about 40. A harder silicone may use thinnerwalls, a softer silicone may use thicker walls. A rounded bellows-likestructure also facilitates flexibility independent of the material it isconstructed from. Another plenum may be molded from polyurethane foam.Prior patient interfaces such as the Fisher & Paykel INFINITY™ 481,OPUS™, OPUS™ 360, and the Respironics OPTILIFE™ include a range of rigidmaterials such as polycarbonate. Other masks such as the AIRSEP™Ultimate mask include rigid headgear connectors.

The patient interface structure 32 may be formed in one piece, forexample by molding a material such as silicone. In one form of thesample embodiment, the range of movement provided by the flexibility ofthe pillows 4 with respect to the top portion 6 t of the flexible base 6may be relatively small compared with the range of movement provided bythe lower part 6 l of the flexible base 6 acting as part of thedecoupling arrangement.

In use, a strap of the seal positioning and stabilizing structure isattached to each seal positioning and stabilizing structure connector12, one on each side of the nose of the patient, for example as shown inFIG. 3, establishing a connection. The connection is close to the planeof the entrance to the nares of the patient. In this way, the straps ofthe seal positioning and stabilizing structure 36 more directly hold thenasal pillows 4 in position than in prior art arrangements, such asshown in FIG. 1, where the connection is displaced from the plane of theentrance to the nares of the patient. Other prior art patient interfacessuch as the Fisher & Paykel INFINITY™ 481, OPUS™, OPUS™ 360, and theRespironics OPTILIFE™ place the point of connection at some distancefrom the nares. The lower portion 6 l of the flexible base 6 acts aspart of a decoupling arrangement between the plane of connection withthe straps of the seal positioning and stabilizing structure 36 and theconnection with the air delivery tube 16 so that tube drag does notdirectly impact the seal formed between the nasal pillows 4 and thenares of the patient.

Referring to FIGS. 8 b and 8 n, a patient interface structure 32according to another sample embodiment may comprise a seal 2 comprisinga nozzle assembly 3 having a pair of nasal pillows 4. The flexible base6 may include integrally formed connectors 50. The patient interfacestructure 32 may be coupled to a decoupling arrangement, e.g. a swivelring, to decouple tube drag forces as will be described in more detail.

Each nasal pillow 4 may include a conical portion 8 and a neck portion10. Each conical portion 8 may comprise a sealing zone 8 a configured toform a seal against the patient's nare. The nasal pillows 4 may beformed with the patient interface structure 32 or may be removablyattached to the patient interface structure 32, for example as describedin WO 2005/063328 A1, the entire contents of which are incorporated byreference. The patient interface structure 32 may further comprise anaperture 46 for introduction of a flow of breathable gas into thepatient interface structure 32. The aperture 46 may be formed in a lowerportion 6 l of flexible base 6 and be surrounded by a flange 48 that isconfigured for engagement with an air delivery tube, or a swivel elbowassembly, or a ball and socket joint. It should also be appreciated thatthe flange 48 of the patient interface structure 32 may be configuredfor connection to a frame or shell.

The patient interface structure 32 may be formed of a flexible material,such as silicone. The patient interface structure 32 may be formed ofone piece, including the nasal pillows 4, the flange 48, and a pair ofconnectors 50 provided at each end of the patient interface structure32. As shown in FIG. 8 b, each connector 50 may comprise a first slot 52and a second slot 54 for receipt of an end of a strap of the sealpositioning and stabilizing structure. The first slot 52 and a secondslot 54 are separated by a crosspiece 56 which may engage the end of thestrap to retain the end of the strap in contact with the connector 50.The patient interface structure, including the connectors 50, isflexible and forces applied by the seal positioning and stabilizingstructure, for example by side straps, stretch the connector 50 toincrease the force that the crosspiece 56 exerts on the seal positioningand stabilizing structure strap.

The patient interface structure 32, including the connectors 50, may beintegrally formed, for example by molding. The patient interfacestructure 32 may be formed so as to have varying densities and/orhardnesses. For example, the nasal pillows 4 and/or the flexible base 6may be formed of a first density and/or hardness and the connectors 50may be formed of a second density and/or hardness. The second densityand/or hardness may be higher than the first density and/or hardness.This permits the patient interface structure 32 to be formed so as tohave a softer feeling in those areas that engage the patient's face(e.g. the nozzle assembly of the seal) and a harder, or more rigid,feeling in the area connected to the seal positioning and stabilizingstructure. The hardness, e.g. durometer, of the patient interfacestructure may be different from the hardness of the seal positioning andstabilizing structure discussed below. For example, the durometer of theconnectors and/or flexible base of the patient interface structure maybe different from the straps and/or the connectors of the straps of theseal positioning and stabilizing structure.

3.2.2 Patient Interface Structure Including Nasal Prongs as Seal

FIGS. 5 a and 6 illustrate an aspect of the present technology wherebythe point of connection of the seal positioning and stabilizingstructure is moved closer to the base of the seal, for example close tothe base of nasal pillows or prongs. Referring to FIG. 5 a, a patientinterface system according to a sample embodiment includes a patientinterface structure 32 a comprising a seal 2 a including a nozzleassembly 3 a. The nozzle assembly 3 a comprises a pair of nasal prongs 4a. Each nasal prong 4 a includes a stalk, or neck portion, 10 a thatconnects the nasal prong 4 a to a flexible base 6 a of the patientinterface structure 32 a. Flaps 4 b are provided between the nasalprongs 4 a and the stalks 10 a. The nasal prongs 4 a form a seal withthe nasal passageways of the patient when the nozzle assembly 2 a isheld by a seal positioning and stabilizing structure in engagement withthe face of the patient.

A pair of seal positioning and stabilizing structure connectors 12 a areprovided on a flexible base 6 a of the patient interface structure 32 a.Connectors 12 a are provided on the flexible base 6 a for the connectionof straps of a seal positioning and stabilizing structure with thepatient interface structure 32 a.

The connectors 12 a may include a plurality of connection points 13 a,13 b to allow the relative position of the patient interface structure32 a with respect to the seal positioning and stabilizing structure 36to be changed or adjusted.

Referring again to FIG. 2, a patient interface system may include thepatient interface structure of FIG. 5 a and a mask shell or frame asshown in FIG. 2 that is modified to not include the connectors on theframe and includes a vent having a plurality of vent holes. The maskframe may be connected to an air delivery tube by a swivel elbow. Theends of the swivel elbow may include ball and socket type connections tothe frame and the air delivery tube so that the swivel elbow acts as adecoupling element or joint. The delivery tube may receive a flow ofpressurized breathable gas by being connected through a coupling elementto a flow generator or blower. It should be appreciated that the maskframe of FIG. 2 may be formed of a flexible material, instead of a rigidmaterial as in the prior art shown in FIG. 2, and the connectors 12 maybe provided on the flexible frame.

In another sample embodiment, the elbow may be flexible. In such a form,it may be desirable to locate the vent holes elsewhere on the masksystem. Alternatively, a solid vent insert may be placed in the flexibleelbow. In another form, reinforcement may be provided to the flexibleelbow to maintain its structural integrity and prevent the tube fromoccluding.

3.2.3 Patient Interface Structure Including Nasal Prongs Seal andConnectors on Nasal Prongs

Referring to FIG. 6, in another sample embodiment, the seal positioningand stabilizing structure connectors 12 a are provided at a point justbelow the flaps 4 b of the nasal prongs 4 a. The seal positioning andstabilizing structure connectors 12 a are connected to the neck, orbase, portions 10 a of the nasal prongs 4 a. According to thisembodiment, the plane of connection formed by the seal positioning andstabilizing structure connectors 12 a is closer to the plane of theentrance to the nares of the patient than the embodiment shown in FIG. 5a. The patient interface structure of FIG. 6 may also be used with amask frame such as shown in FIG. 2 that is modified to not includeconnectors on the frame. It should also be appreciated that the patientinterface structure of FIG. 6 may be used with a mask frame such asshown in FIG. 2 that is modified to be formed of flexible material.

3.2.4.1 Patient Interface Structure Including Linking Element—FirstEmbodiment

Referring to FIGS. 8 a and 8 b, a patient interface structure according32 according to another sample embodiment may comprise a seal 2comprising a nozzle assembly 3 having nasal pillows 4. The patientinterface structure 32 may include an optional linking portion orelement 47 configured to link tension forces applied by the sealpositioning and stabilizing structure from one side of the patientinterface structure 32 to the other side in order to isolate forcesapplied by the seal positioning and stabilizing structure at the topportion 6 t of the flexible base 6, and thereby isolate tube drag forcesat the lower portion 6 l of the flexible base 6 of the patient interfacestructure 32. By isolating forces in such a way, the sealing zones 8 aof the nasal pillows 4 of the seal 2 are stabilized against thepatient's nares in use. In some forms of the technology, there may be nophysical linking element. The line of force defined by the linkingelement is preferably close to the base of the nose when used in anunder-the-nose type mask such as nasal pillows or nasal prongs.

As shown in FIG. 8 a, the linking element 47 may take the form of astiffened and/or reinforced top portion 6 t when compared to the lowerportion 6 l of the flexible base 6. The lower portion 6 l may include,or take the form of, a gusset, for example as disclosed in WO 01/97893A1. The gusset may also be configured similarly to an accordion, havingmultiple ridges to increase its springiness and flexibility, for exampleas disclosed in WO 2006/074515 A1, the entire contents of which areincorporated herein by reference.

The gusset may also be reinforced to control where and how it collapses,i.e. so that it can move laterally and axially but cannot compressvertically. Reinforcement may include supporting ribs, thickenedsections or regions, or a rigid or semi-rigid skeleton with a flexiblematerial surrounding it.

Stiffening and/or reinforcing may be achieved by a thickening of thematerial used in the patient interface structure 32, for exampleincreasing the thickness of the silicone by up to about 10 mm at the topportion 6 t when compared to the lower portion 6 l of the flexible base6. Such stiffening and/or reinforcing may also be achieved through theuse of a higher hardness material positioned at the top portion 6 t, forexample silicone of a durometer between about 50-80 on the Shore Ahardness scale. Additionally, or alternatively, metal inserts, forexample a wire(s) or mesh(es), may be used in the linking element 47.Stiffening and/or reinforcing may also be achieved by a gel insert. Thegel insert may also increase patient comfort, for example at the septum.Furthermore, stiffening and/or reinforcing may also be achieved by afoam insert. The foam insert may increase patient comfort, for exampleat the septum, and act as a secondary seal should a leak form at theprimary seal. The linking element 47 may also be formed of a co-molded,generally inextensible material, for example nylon, TPE, metal, oralloy. The linking element 47 may also be in the form of a beaded,thickened portion, as described in more detail below. Desirably,stiffening and/or reinforcing the top portion 6 t, for example to formthe linking element 47, will result in the lower portion 6 l being moreextensible so that forces applied by the seal positioning andstabilizing structure are more isolated from the lower portion 6 l. Thisallows the lower portion 6 l of the flexible base 6, for example thegusset, to flex more easily while ensuring that the nasal pillows 4 areheld in sealing contact with the nares of the patient.

In another form, the linking element 47 may be configured in such a waythat it is stiff along its length, e.g. from connector 50 to connector50, but elastic through its height, i.e. in the general direction of thenasal pillows 4. This enables the neck portions 10 of the nasal pillows4 to flex more readily while maintaining the primary function of thelinking element 47, i.e. isolating the forces applied by the sealpositioning and stabilizing structure.

In a variant, the linking element 47 may be formed from a material thatcan be molded to the patient's face, for example the plastic materialused to form mouth guards. This would provide the benefit of isolatingforces and increasing the comfort of the patient interface system due toits unique fit.

3.2.4.2 Patient Interface Structure Including Linking Element—SecondEmbodiment

As shown in the sample embodiment of the patient interface structureshown in FIG. 8 a, the linking element 47 may extend across the entiretop portion 6 t of the flexible base 6, from connector 50 to connector50, and including the entire width. See, for example, W1 in FIG. 17 a.According to another sample embodiment of the patient interfacestructure 32 shown in FIG. 8 c, the linking element 47 may extend over asection, or sections, of the top portion 6 t of the flexible base 6, forexample only the section of the top portion 6 t between the nasalpillows 4. The linking element 47 may cover a fraction of the width ofthe top portion 6 t, for example half the width. The tension linkingelement 47 may cover a section, or sections, of the top portion 6 t aslong as it is sufficient to isolate the forces as described above.

3.2.4.3 Patient Interface Structure Including Linking Element—ThirdEmbodiment

Referring to FIG. 8 d, the linking element may be formed as a series ofridges 47 a. The number of ridges 47 a may be determined in order tosufficiently isolate forces as described above. As shown in FIG. 8 d,the ridges 47 a may be provided to the top portion 6 t only between thenasal pillows 4. The ridges 47 a may be thicker than the top portion 6t. The ridges 47 a may be generally circular or rectangular or any othershape. The ridges 47 a may extend upwards and/or downwards from the topportion 6 t. The ridges 47 a may also be formed from a material ofhigher hardness than that used to form top portion 6 t, for examplehigher durometer silicone, or metal. The ridges 47 a may be formed inone piece with the patient interface structure 32, or may be retrofittedto the patient interface structure 32. For example, the linking element,e.g. the ridges 47 a, may be adhesively attached to the patientinterface structure 32. The ridges 47 a may also be independent of oneanother, or the ridges 47 a may be joined together. In the case of thelinking elements comprising inserts, the inserts may be separatelyprovided, or connected together. The ridges 47 a may also be formed ofindividual shapes, sizes, thicknesses, materials, and/or hardnesses.

3.2.4.4 Patient Interface Structure Including Linking Element—FourthEmbodiment

Referring to FIG. 8 e, the ridges 47 a may be provided to the topportion 6 t along the entire length of the flexible base 6, i.e. fromconnector 50 to connector 50.

3.2.4.5 Patient Interface Structure Including Linking Element—FifthEmbodiment

Referring to FIG. 8 f, the linking element 47 may be formed in the topportion 6 t of the flexible base 6 of the patient interface structure32. For example, the patient interface structure 32 may be molded aroundthe linking element 47 so that the linking element 47 is embedded withinthe top portion 6 t of the flexible base portion 6 of the patientinterface structure 32. The linking element 47 may be formed, forexample, of metal or plastic material. The linking element may also bein the form of, for example, a wire or a mesh.

3.2.4.6 Patient Interface Structure Including Linking Element—SixthEmbodiment

Referring to FIGS. 8 g and 8 h, according to another sample embodiment,the linking element 47 may be provided along the top portion 6 t of theflexible base 6. The linking element 47 may include slots or openings 47o that correspond with the first and second slots 52, 54 of theconnector 50 to accept the straps of the seal positioning andstabilizing structure that connect to the patient interface structure32. As shown in FIG. 8 h, the linking element 47 may have an outlinethat matches the top portion 6 t of the flexible base 6 of the patientinterface structure 32 and comprise openings 47 p that are configured toreceive the stalks or neck portions 10 of the pillows 4. The linkingelement 47 may also include slits 47 s that allow the portions of thelinking element 47 around the openings 47 p to be displaced with respectto one another to insert the linking element 47 over the pillows 4 andonto the top portion 6 t of the flexible base 6.

The element 47 may be formed of, for example, metal or plastic. Forexample, the linking element 47 may be a thin metal sheet that isstamped into the configuration shown in FIG. 8 h. It should also beappreciated that the connectors 50 of the patient interface structure 32may be eliminated and the straps of the seal positioning and stabilizingstructure connected directly to the linking element 47 without anydirect connection to the patient interface structure 32.

3.2.4.7 Patient Interface Structure Including Linking Element—SeventhEmbodiment

Referring to FIGS. 8 i and 8 j, a linking element 47 may extend aroundthe neck portions 10 of the pillows 4. As shown in FIG. 8 j, the linkingelement 47 may have a figure eight configuration and include openings 47p that are configured to receive the neck portions 10 of the pillows 4.The linking element 47 may be formed from, for example, metal orplastic. For example, the linking element 47 may be formed from a wire.

3.2.4.8 Patient Interface Structure Including Linking Element—EighthEmbodiment

Referring to FIG. 8 k, according to another sample embodiment, thelinking element 47 may comprise a bridging portion between the stalks orneck portions 10 of the nasal pillows 4. The linking element 47 may beintegrally formed, e.g. by molding, with the patient interface structure32. The linking element 47 may also be formed of a different materialthan the material used to form the patient interface structure 32. Forexample, the linking element 47 may be formed of a higher durometermaterial than the patient interface structure material. The linkingelement 47 may be formed to be more rigid than the top portion 6 t ofthe flexible base 6 of the patient interface structure 32.

3.2.5 Nasal Pillow Seals—Offset

Referring to FIGS. 27 a and 27 b, each nasal pillow 4 may comprise apillow orifice 5 for delivering breathable gas to the nares of thepatient. Each pillow 4 is inserted into a nare of the patient and issealed at a sealing surface 11. As shown in FIG. 27 b, the pilloworifice 5 is offset from a neck orifice 9 of the stalk or neck portion10 along a major axis 13 of the elliptically shaped nasal pillow 4 byshifting the pillow orifice 5 along the major axis 13. The portion 11 aof the sealing surface 11 that is in contact with the upper lip of thepatient is thus reduced, which may increase patient comfort. Althoughthe pillow orifice 5 is shown shifted from the neck orifice 9 along themajor axis 13, it should be appreciated that the pillow orifice 5 may beshifted along the major axis 13 and/or the minor axis 15.

3.2.6 Nasal Pillows Seal Including Dual Walls

Referring to FIGS. 17 a-17 f, a patient interface structure 320 includesconnectors 322 on each side and connected to a flexible base 329 of thepatient interface structure 320 by extensions 323. It should beappreciated that the connectors 322 may be connected by the extensions323 to respective neck portions 332 of a pair of nozzles 328 in a mannersimilar to that discussed above with respect to FIG. 6. The connectors322 may be linear with the upper surface of the flexible base 329 (asshown in FIGS. 17 b and 17 d). Alternatively, the connectors 322 may betilted or angled to alter the position of the patient interfacestructure 320 when connected to the seal positioning and stabilizingstructure.

The patient interface structure 320 comprises a seal 333 comprising anozzle assembly comprising the pair of nozzles taking the form of nasalpillows 328. As shown in FIGS. 17 b and 17 d, the pillows 328 eachcomprise a neck portion 332 that is connected to the flexible base 329that defines a nasal breathing cavity 336. As also shown in FIGS. 17 dand 17 e, each nasal pillow 328 comprises an inner conical portion 334and an outer conical portion 330. Such pillows are disclosed, forexample, U.S. Patent Application Publications 2007/0144525 A1 and2006/0283461 A1, the entire contents of each being incorporated hereinby reference. It should also be appreciated that the nasal pillows maybe as described in, for example, U.S. Pat. No. 7,318,437, the entirecontents of which are incorporated herein by reference. The outerconical portion 330 comprises a sealing surface, or zone, 330 a that isconfigured to seal against the patient's nare. As shown in FIG. 17 d,the inner conical portion 334 and the outer conical portion 330 may havedifferent thicknesses.

Referring to FIGS. 17 d, 17 f and 17 g, the flexible base 329 includesan aperture 324 for the introduction of the flow of breathable gas. Theflexible base 329 further comprises a flange 326 that extends radiallyinwardly and defines the aperture 324. The flange 326 may comprise achamfer 327 for insertion of a swivel sealing ring as discussed in moredetail below. The flexible base 329 of the patient interface structure320 may thus be connected to a frame, a swivel elbow, or a tube orconduit as also described in more detail below.

It should also be appreciated that the flexible base 329 may include alinking element(s), similar to the one disclosed and discussed withrespect to FIGS. 8 a-8 g,for example in between the neck portions 332 ofthe nasal pillows 328.

Referring to FIG. 17 a, the aperture 324 may have a diameter D1 of about17 mm-20 mm, for example about 18.5 mm. The patient interface structure320 may have a width W1 of about 25 mm-35 mm, for example about 30.5 mm.The patient interface structure 320 may have a length L1 of about 80mm-90 mm, for example about 84.5 mm. The seal positioning andstabilizing structure connector 322 may have a length of about 12 mm-18mm, for example about 15.5 mm.

Referring to FIG. 17 d, the flexible base 329 may have a length L3 ofabout 45 mm-50 mm, for example about 47.5 mm. The patient interfacestructure 320 may be a height H1 of about 30 mm-37 mm, for example about33 mm. The base portion 329 may have a height H2 of about 15 mm-23 mm,for example about 19 mm.

Referring to FIGS. 17 d and 17 g, the extensions 323 may have athickness T1 of about 1.5 mm-2.0 mm, for example about 1.8 mm. Theflexible base 329 may have a thickness T2 between the nasal pillows 328of about 1.5 mm-2.5 mm, for example about 2.0 mm. It should beappreciated that the thickness T2 may be greater, for example in thecase where a linking element is formed in one piece with the patientinterface structure 320 between the nasal pillows 328. The flange 326may have a thickness T3 of about 1.5 mm-2.5 mm, for example about 2.0mm. The flexible base 329 may have a thickness T4 of about 0.6 mm-1.0mm, for example about 0.8 mm.

The stalks 32 may have a length of about, for example, 3 mm to about 6mm.

3.2.6.1 Nasal Pillows Seal Including Dual Walls—Equal Displacement andNon-Concentric

Referring to FIGS. 29 a and 29 b, the pillows 328 may comprise the outerconical portion 330 and the inner conical portion 334. A portion 360 aof a sealing zone 360 of the outer conical portion 330 that is incontact with the upper lip of the patient is displaced an equal distance362 from the stalk or neck portion 332 of the pillow 328 as a portion360 b of the sealing zone 360 that is in sealing engagement with thenares of the patient. The sealing zone 360 and the pillow orifice 354are non-concentric with the stalk 332 of the pillow 328.

3.2.6.2 Nasal Pillows Seal Including Dual Walls—Unequal Displacement andConcentric

Referring to FIGS. 30 a and 30 b, the portion 360 a of the sealing zone360 that engages the upper lip of the patient is displaced a distance364 that is not equal to the distance 366 that the portion 360 b isdisplaced from the stalk 332. The pillow orifice 354 and the sealingzone 360 are concentric with the stalk 332.

3.2.6.3 Nasal Pillows Seal Including Dual Walls—Unequal Displacement andConcentric with Supporting Rib

Referring to FIGS. 31 a and 31 b, the portion 360 a is displaced anunequal amount from the stalk 332 than the sealing zone portion 360 b.The sealing zone 360 and the pillow orifice 354 are concentric with thestalk 332. A supporting rib 368 may be provided under the portion 360 bof the sealing zone 360 to maintain the pillow sealing zone in anupright position so that it may seal at the nares.

3.2.6.4 Nasal Pillows Seal Including Dual Walls—Concentric and Angled

As shown in FIGS. 32 a and 32 b, the inner conical portion 334 and theouter conical portion 330 are tilted at an angle 370 with respect to thestalk 332 of the pillow 328. The angle tilts the pillow towards the faceof the patient and may be, for example, −30° to 45°, as another example15°. The portion 360 a configured to engage the upper lip of the patienthas a larger radius than the sealing zone portion 360 b to provide forgreater patient comfort. The pillow orifice 354 and the sealing zone 360are eccentric with respect to the stalk 332.

3.2.6.5 Nasal Pillows Seal Including Dual Walls—Symmetrical, Concentricand Angled

Referring to FIGS. 33 a-33 f, the orifice of the inner conical surface1100, the outer 1000 walls and stalk 1200 of the nasal pillow 1150 areconcentric with respect to a center line CL. The radius of the portion1600 on the opposite side to portion 1500 is smaller than the radius ofthe portion 1500 that is adjacent to the upper lip of the patient. Thelarger radius of portion 1500 has a thickened region 1550 that assistsin avoiding contact between the nasal pillow and the top lip, pushingthe structure away therefrom. Avoiding contact with the top lip canimprove comfort for some patients. An advantage of this is that the needto provide a separate manual pillows rotation mechanism may be reducedsince the pillow may automatically move away from the top lip, adjustingto the naso-labial angle of the patient. This may in part be assisted byflexure of the patient interface structure connectors 84 of the sealpositioning and stabilizing structure.

The base of the pillow 1150 is angled with respect to the top of alinking element 1400. The angle a allows the linking element 1400 totilt. Referring to FIG. 33 d, to engage the pillows 1150 with andentrance to the patient's airways, the pillows are placed at the entryto the nares. As shown in FIG. 33 e, as the seal positioning andstabilizing structure is adjusted, strap tension begins to pull thepillows into the nares. Continued insertion of the pillows into thenares causes the stalk 1200 to collapse into the linking element 1400via trampoline 1300, moving the linking element 1400 into contact withbase of pillows 1150.

The thickened region 1550 results in a relatively stiffer springstructure than the thinner portion 1600 that may rotate the patientinterface structure away from the top lip. Since the base of the pillow1150 is angled α with respect to the linking element 1400, the linkingelement 1400 aligns with the base of the pillow 1150 so that they areflush or in constant contact along the whole surface of the base of thepillows 1150. This means that the linking element 1400 and adjacenttrampoline 1300 rotates upwards, i.e. rotates by α° towards the top ofthe patient's nose. The linking element 1400 and the trampoline 1300 arethereby angled away from the bottom of the pillows or upper lip of thepatient. This improves the comfort and stability of the patientinterface system.

The rotation of the trampoline 1300 and the linking element 1400 awayfrom the patient's upper lip could similarly be achieved by skewing theshape of the trampoline 1300 and/or linking element 1400 (e.g. byaltering the dimensions of the flexible base of the patient interfacestructure), change the trampoline properties so that it is stiffer insome regions compared to other regions to force the stalk to collapse ina certain way (e.g. stiffer towards the bottom of the pillows/upper lipside) or changing the properties of the stalk to cause it to collapsemore in one direction than another (e.g. stiffer towards the bottom ofthe pillows/upper lip side).

3.2.6.6 Nasal Pillows Seal Including Dual Walls—Offset Inner and OuterConical Portions

Referring to FIGS. 34 a and 34 b, the nasal pillows 328 may compriseelliptical inner and outer conical portions 334, 330, respectively. Asshown in FIGS. 34 a and 34 b, the orifices 354, 355 of the inner andouter conical portions 334, 330, respectively, may be offset along amajor axis of the ellipses. The radius of the portion 360 a of thesealing zone 360 configured to engage the upper lip of the patient islarger than the radius of the portion 360 b configured to seal the nareof the patient.

3.2.7 Nasal Pillows Seal—Truncated

Referring to FIG. 35, the pillows 328 may be provided with cut outs, ortruncated portions, 350 for improved upper lip comfort of the patient.As shown in FIG. 36, according to one variant, the pillow orifice 354,the sealing zone 360, and the stalk 332 are concentric. The upper lipcontacting side of the pillow 328 includes a truncated portion 350 toprevent interference and discomfort.

As shown in another variant illustrated in FIG. 37, the pillow orifice354 and the sealing zone 360 are concentric along the centerline 358.The stalk 332 is not concentric with the centerline 358 so that thestalk orifice 356 is offset from the pillow orifice 354. As shown inFIG. 37, the stalk 332 may be offset in a direction away from thetruncated portion 350. In a further variant shown in FIG. 38, the stalk332 may be offset in a direction towards the truncated portion 350.

3.2.8 Nasal Pillows Seal—Coincident Sealing Surface and Stalk

As shown in FIGS. 39 a and 39 b, the stalk 332 may be provided at aposition coincident with the portion 360 b of the sealing zone 360 thatis configured to engage the patient's upper lip.

3.2.9 Nasal Pillows Seal—Bent Stalk and/or Sealing Surface

Referring to FIGS. 40 a-40 h, the outer conical portion 330 of thepillow 328 may be provided at an angle with respect to the stalk 332and/or the stalk may be angled and/or have a variable cross section.

3.2.10 Nasal Pillows Seal—Rose Bud

As shown in FIG. 41, the nasal pillows 328 may be conjoined. Theportions 360 a of the sealing zones configured to contact the patient'supper lip may have a shallow radius and the portions 360 b configured toengage the nares may have a large radius at the outer edges of thesealing zones to increase the fit range of the pillows. The pillows 328may have a generally rose bud shaped configuration, as shown in thedrawings.

3.2.11 Nasal Pillows Seal—Olive

Referring to FIG. 42, the sealing zone of the pillow may have a largeradii on either side, or both sides. The pillow may act as a nasaldilator. As shown in the drawings, the pillows 328 may have a generallyolive shaped configuration.

While various sample embodiments discussed above have been describedwith respect to nasal pillows or prongs, it should be appreciated thatother forms of nozzles or nare seals maybe used, for example asdisclosed in U.S. Pat. No. 4,782,832 (Trimble), U.S. Pat. No. 7,201,169(Wilkie et al.), U.S. Pat. No. 7,059,328 (Wood), and WO 2000/074758(Lovell).

3.2.12 Patient Interface Structure Including Foam Seal

Referring to FIGS. 46 a-46 e, a patient interface system according toanother sample embodiment includes a patient interface structure 32 thatincludes a flexible base 6. A seal 2 is provided on the flexible base 6.The seal 2 may be formed of foam. A swivel elbow 17 is connected to theflexible base 6 for delivery of a flow of breathable gas from a hose ortube or conduit (not shown) connected to the swivel elbow 17 into anasal breathing cavity defined by the flexible base 6 and the seal 2.

The patient interface structure 32 is held in sealing engagement withthe patient's face by a seal positioning and stabilizing structure 36that comprises side straps 38, a top strap 40 (FIG. 46 c), and a rearstrap (not shown). Although the side straps 38 are shown connected tothe flexible base 6 in an integral fashion, it should be appreciatedthat the side straps 38 may be connected to the flexible base 6 in amanner that allows connecting and disconnecting the side straps 38 fromthe flexible base 6, for example as discussed in more detail herein. Itshould also be appreciated that one, or both, side straps 38 may beconfigured to be connectable and disconnectable from the flexible base6.

As shown in FIG. 46 b, the seal 2 includes an aperture 19 that isconfigured to surround both nares of the patient. As shown in FIG. 46 c,the flexible base 6 is conformable and in use wraps around the nose ofthe patient 1. As also shown in FIGS. 46 c-46 e, the seal 2 may beconfigured to seal in part above the tip of the patient's nose.

3.3 Seal Positioning and Stabilizing Structure 3.3.1 Seal Positioningand Stabilizing Structure—First Embodiment

Referring again to FIGS. 7 a-7 c, the seal positioning and stabilizingstructure 36 may be formed, for example, from a flat silicone sheet.Typically, a headgear for a respiratory mask is formed from a foam andfabric laminate, such as BREATHOPRENE®. Such headgear is die cut andthus has squared edges. This can appear bulky on the face of the patientand can be uncomfortable due to its edges. In the sample embodimentsdisclosed herein, seal positioning and stabilizing structure made fromsilicone may be molded to have rounded edges. Such rounded edges improvecomfort. In one form, the rounded edges may have a radius of greaterthan about 0.5 mm. As shown in FIG. 7 b, the straps 38, 40, 42 of theseal positioning and stabilizing structure 36 may have the rounded edges420 formed on the patient contacting (i.e. skin contacting) side 418 ofthe straps 38, 40, 42. The parting line 416 of the tool that forms thestraps 38, 40, 42 may be further from the patient contacting side 418 toavoid flash near the patient's face that can cause irritation. As shownin FIG. 7 c, the straps 38, 40, 42 may include a larger radius 422 onthe patient contacting side 418 by providing portions 424 on theopposite side that are rolled back from the parting line 416.

Other polymers, e.g. TPE, may be used to form the seal positioning andstabilizing structure 36. The seal positioning and stabilizing structure36 may include two side straps 38 (only one visible in FIG. 7 a), a topstrap 40, and a rear strap 42. Respective ends 38 a of the side straps38 are connected to connectors 12 (only one visible in FIG. 7 a)provided on the flexible base 6 of the patient interface structure 32.The connectors 12 are located on sides of the flexible base 6 to whichnasal pillows may be connected. The connection of the connectors 12 tothe flexible base 6 enables the flexible base 6 to wrap around the baseof the nose of the patient and be pulled back to retain the nasalpillows in a sealing relationship with the underside of the patient'snose.

The respiratory mask system of FIG. 7 a may be adjusted by adjusting theconnection of the ends 38 a of the side straps 38 with the connectors12. For example, the connectors 12 may each include a slot, or slots,configured to accept the end 38 a of the side strap 38. The sealingforce provided by the seal positioning and stabilizing structure 36 maybe adjusted by adjusting the ends 38 a of the side straps 38. Forexample, to increase the sealing force applied by the seal positioningand stabilizing structure 36, the patient 1 may pull on the end(s) 38 aof the side strap(s) 38. The sealing force may be decreased byshortening the end(s) 38 a of the side strap(s) 38, e.g. by pulling theside strap(s) 38 back through the connector(s) 12. The patient interfacestructure 32 may be rotated with respect to the seal positioning andstabilizing structure 36 about an axis generally parallel to a linedrawn through both eyes of the patient and below the patient's nose bythe inherent flexibility of the straps. It should also be appreciatedthat inelastic straps may be used. It should be further appreciated thatangular adjustment of the patient interface structure 32 with respect tothe seal positioning and stabilizing structure 36 may be achieved by anadjustment buckle(s)/connector(s), such as those disclosed, for example,in U.S. Pat. No. 6,907,882, the entire contents of which areincorporated herein by reference.

3.3.2 Seal Positioning and Stabilizing Structure—Second Embodiment

Referring to FIG. 10, in another sample embodiment , the sealpositioning and stabilizing structure 36 may comprise a strap 41configured to encircle the patient's head at a position above thepatient's ears. A side seal positioning and stabilizing structure strap38 (only one visible in FIG. 10) extends along each side of the face ofthe patient 1 and is connected to a respective side of the patientinterface structure 32. The patient interface structure may be connectedto a swivel elbow or joint 17 through a decoupling arrangement 34,although it should be appreciated that the patient interface structuremay be connected to a rigid, or semi-rigid, frame or shell. The swivelelbow is connected to an air delivery tube 16 for the delivery of theflow of pressurized breathable gas.

A stiffening, or reinforcing, element 66 may be connected to each sidestrap 38. As shown in FIG. 10, in order to avoid impingement on thevision of the patient 1, the stiffening or reinforcing element 66traverses the eye socket of the patient 1. The provision of thestiffening elements thus allows for the force vectors of the sealpositioning and stabilizing structure to pass near the eyes of thepatient without obscuring the patient's vision. Hence a tension forcemay be directed in a more ideal direction, orthogonal to the sealingsurface, in this case the underside of the patient's nose.

The stiffening element 66 may be constructed from a materialsufficiently stiff along the longitudinal length to resist bending underthe seal positioning and stabilizing structure tension forces, but ableto conform in an out of plane direction to lie flat on the patient'sface. Suitable materials for the stiffening elements 66 include, forexample, nylon, polypropylene, and silicone.

The stiffening elements 66 may be threaded through the side straps 38,or the stiffening elements 66 may be adhered or stitched in place on theside straps 38. Alternatively, the stiffening elements may be movable onthe side straps 38 of the seal positioning and stabilizing structure 36,for example, by sliding along the side straps 38.

3.3.3. Seal Positioning and Stabilizing Structure—Third Embodiment

Referring to FIG. 11, in another sample embodiment, the top strap 40 maybe configured to extend at an angle to the rear strap 42. Thisconfiguration produces force vectors that increase the sealing forceapplied by the seal positioning and stabilizing structure 36 withoutincreasing the tension. A component of the force provided by the topstrap 40 is directed upward, which increases the sealing forces appliedto the patient interface structure 32. In other words, the sealing forcecomponent of the top strap 40 is added to the sealing force component ofthe side straps 38 to provide improved sealing without increasingtension.

3.3.4 Seal Positioning and Stabilizing Structure—Fourth Embodiment

Referring to FIGS. 12 a and 12 b, a patient interface system accordingto another sample embodiment comprises a seal positioning andstabilizing structure 36 connected to a patient interface structure 32by lateral side arms 68 provided on each side of the face of the patient1. Each lateral side arm 68 may comprise a first side arm connector 68 aconnected to the patient interface structure and a second side armconnector 68 b, with respect to the orientation shown in FIG. 12 a,below the first side arm connector 68 a, connected to the patientinterface structure 32. The lateral side arm 68 may be connected to therear strap 42 of the seal positioning and stabilizing structure 36through a slot 68 c provided in the lateral side arm 68 that receivesthe rear strap 42. As shown in FIGS. 12 a and 12 b, a side strap 38 ofthe seal positioning and stabilizing structure 36 may extend along aportion of the lateral side arm 68. It should be appreciated, however,that the side strap 38 may be eliminated and the lateral side arm 68 mayextend from the junction of the top strap 40 and the rear strap 42. Eachlateral side arm 68 may be configured to lie on the face of the patientfrom a point in the general region of the temple to near the base of thepatient's nose.

The lateral side arms 68 may be formed of material similar to thestiffening elements described above with reference to FIGS. 10 and 11.Alternatively, the lateral side arms 68 may be formed from a softflexible material, for example a laminate of compressed foam and fabricmaterial, such as BREATHOPRENE®. The lateral side arms 68 may beconstructed to be sufficiently stiff along the longitudinal length toavoid bending under the seal positioning and stabilizing structuretension forces, but able to conform in an out of plane direction to lieflat on the patient's face.

The first and second side arm connectors 68 a, 68 b are connected to thepatient interface structure 32 at two points and are sufficiently wideat the connections to improve control over the rotational stability ofthe seal, but permit rotation of the patient interface 32 to present theseal, e.g. nasal pillows, at a right angle to the sealing surface.

3.3.5 Seal Positioning and Stabilizing Structure—Fifth Embodiment

Referring to FIGS. 13 a and 13 b, the lateral side arms 68 may beconnected to the side straps 38 through slots 68 c. The side straps 38may be connected to the strap 41 by a strap connector 70. The side strap38 is connected at one end to the strap connector 70 and at the oppositeend to the lateral side arm 68 through the slot 68 c. The strapconnector 70 may be moved along the strap 41 to allow the patient toadjust the position of the lateral side arms 68. The patient may thusadjust the position of the lateral side arm 68 to effect a good sealbetween the patient interface structure 32 and the nares of the patient,and the patient interface system may be adjustable to fit patients of avariety of sizes.

3.3.6 Seal Positioning and Stabilizing Structure—Sixth Embodiment

Referring to FIGS. 14 a and 14 b, according to another sample embodiment, the seal positioning and stabilizing structure 36 may be formed of asingle piece, including the top strap 40, the rear strap 42, the sidestrap 38 and the lateral side arms 68. A buckle 71 may be provided onthe top strap 40 to adjust the fit of the seal positioning andstabilizing structure 36 to the patient. It should be appreciated thatthe buckle may be provided additionally or alternatively to the rearstrap 42. The single piece seal positioning and stabilizing structure 36may be connected to the patient interface structure 32 by connectorssuch as hook and loop fasteners. Alternatively, the single piece sealpositioning and stabilizing structure 36 may be a complete circularcomponent that can wrap around the patient interface structure 32 at,for example, the base of the patient interface structure 32 between thepatient interface structure 32 and the elbow 17, or at the top of thepatient interface structure 32 between the flexible base of the patientinterface structure 32 and the seal (e.g. nozzle arrangement). Inanother sample embodiment, the entire patient interface system,including the patient interface structure 32 and the seal positioningand stabilizing structure 36 may be formed as a single component.Additionally, the elbow 17 may also be formed with the patient interfacestructure 32 and the seal positioning and stabilizing structure 36.

As shown in FIGS. 14 a and 14 b, and FIGS. 12 a-13 b, the lateral sideportions 68 may divide into first and second side arm connectors 68 a,68 b to form a triangular cut out proximal to the patient interfacestructure 32, as shown in the figures. The lengths of the first andsecond side arm connectors 68 a, 68 b affect the angle at which thepatient interface structure 32 is positioned. For example, if the firstside arm connector 68 a is longer than the second side arm connector 68b, the patient interface structure 32 is likely to rotate away from thepatient's nares. Conversely, if the second side arm connector 68 b islonger than the first side arm connector 68 a, the patient interfacestructure 32 is likely to rotate towards the patient's nares. In anothersample embodiment, the length of the first side arm connector 68 a maybe adjustable, thereby rotating the patient interface structure 32, byan adjustment mechanism, such as a buckle. Similarly, adjustment may beprovided to the second side arm connector 68 b to alter its length andthus rotate the patient interface structure, for example by anadjustment mechanism such as a buckle. Adjustment may also be providedto both the first side arm connector 68 a and the second side armconnector 68 b to allow greater adjustment of the patient interfacestructure 32.

3.3.7 Seal Positioning and Stabilizing Structure—Seventh Embodiment

Referring to FIGS. 15 a and 15 b, according to another sampleembodiment, the side strap 38, the top strap 40, and the rear strap 42of the seal positioning and stabilizing structure 36 are connected by aconnector 72. The side strap 38 may be connected to the patientinterface structure 32 by a seal positioning and stabilizing structureconnector 12 which is provided on the patient interface structure 32.The patient interface structure 32 may be connected directly to an airdelivery tube 16 by a swivel elbow 17. The connector 72 allows theposition of each of the straps 38, 40, 42 to be adjusted to allow thepatient to effect a seal between the patient interface structure 32 andthe airways of the patient and allows the seal positioning andstabilizing structure 36 to be sized and fitted to a variety ofpatients.

3.3.8 Seal Positioning and Stabilizing Structure—Eighth Embodiment

FIGS. 24 m-24 q show a patient interface assembly including an eighthembodiment of a seal positioning and stabilizing structure. The sealpositioning and stabilizing structure includes a main strap loop 74, andrear strap 85. With reference to FIG. 24 q main strap loop 74 includes astrap connector 82 arranged to connect rear strap 85 at an angle A withrespect to the crown engaging top portion main loop 74 of about 90° toabout 140°, preferably about 95° to about 110°, most preferably about100°. The closer the angle A is to the preferred values there is aprogressive improvement in the fit range of the headgear, allowing thepatient interface to comfortably fit a range from smaller to largerheads.

With further reference to FIGS. 24 q, 16 a and 16 d, the main strap loop74 has a curved middle portion in between two generally straightportions. The first straight portion lies over the crown of thepatient's head in use. The second straight portion has one end connectedwith a lateral portion of the patient interface structure, and isgenerally parallel therewith. The curved middle portion corresponds tothe stiffened region 78 discussed below. The angle B between the twostraight portions is preferably in the range of about 150° to about 90°,for example about 130° to about 90°, more preferably about 120° to about100°, most preferably about 111°. The closer the angle B is to thepreferred values there is a progressive improvement in the fit range ofthe headgear, allowing the patient interface to comfortably fit a rangefrom smaller to larger heads. Furthermore, the stiffened, curvedportions allows headgear tension forces to be applied to the undersideof the patient's nose at a more effective angle, preferably orthogonalto the underside of the nose, without the headgear obscuring thepatient's vision, or contacting sensitive eye regions. In the preferredarrangement there is no sharp change in direction, compared to forexample, the ResMed Swift® LT. Furthermore this headgear (i.e. sealpositioning and stabilizing structure) arrangement avoids impinging onpatient's ears in a wider range of head sizes.

Referring to FIGS. 47 a and 47 b, an angle Y between a line generallyperpendicular to the strap connector 82 and a line extending through thefirst end of the strap loop 74 may be in a range of from 90° to about140°, preferably about 95° to about 125°, most preferably about 100°.

Referring to FIGS. 16 a-16 g, as discussed previously with respect toFIGS. 45 a and 45 b, the seal positioning and stabilizing structure mayinclude a main strap loop 74 including right and left main straps 74 r,74 l, shown in FIG. 16 d and FIG. 16 a, respectively. Each main strap 74r, 74 l may include a first flexible region 76, a stiffened region 78,and a second flexible region 80. As shown in FIGS. 16 a-16 g, thethicknesses of the regions 76, 78, 80 along the main strap 74 r, 74 lmay be varied to enable the main strap 74 r, 74 l to be sufficientlystiff in areas under load and flexible in areas where conformance to theface is required. The first flexible region 76 is thinner than thestiffened region 78 and may have a thickness of about 0.5 mm-1.5 mm, forexample about 1 mm. The second flexible region 80 is also thinner thanthe stiffened region 78 and may have a thickness of about 1 mm-3 mm, forexample 2 mm. As shown in FIGS. 16 b, 16 c, and 16 e, the secondflexible region 80 may have a varying thickness and the second flexibleregion may have increased flexibility at its thinnest portion. Thestiffened region 78 is thicker than the first and second flexibleregions 76, 80 and may have a thickness of about 3 mm-10 mm, for exampleabout 6 mm.

Preferably the main strap loop 74 is molded from a silicone having aShore A hardness in the range of about 40 to about 80, more preferablyin the range of about 60 to about 70, most preferably about 65. Makingthe main strap loop 74 from a harder silicone makes it stiffer, and mayallow it to be thinner than were it to be made from a softer silicone.Preferably the main loop 74 is not an air delivery tube, or not attachedto an air delivery tube, although it may be either. Using the main loopas an air delivery tube, or coupled to one may reduce the benefitsprovided by the decoupling arrangements. While the main loop 74 madefrom the preferred silicone and thickness is more flexible than a foamand fabric structure reinforced with nylon stiffeners, it has sufficientstructure that it retains a degree of shape when standing by itself,facilitating use by patients who might otherwise be confused by anoverly floppy headgear structure that gives few clues as to how itshould be used. Furthermore, making the main loop 74 from silicone inthe preferred hardness range, and in the preferred thickness rangesmeans that improved stability of the seal may be provided, avoidance ofsensitive regions of the face, and improved fit range without requiringthe use of harder or stiffer materials (e.g. nylon stabilizers) that maycut into the patient's skin, or leave marks on their face. The curvedshape of the stiffened region reduces or eliminates the need for harder,stiffer stabilizers that may be required were the angle between thecrown-engaging top portion and the front portion of the main loop 74sharper. Furthermore, the use of silicone in the main loop provides adegree of flexure upon movement of the air delivery tube, decoupling itfrom affecting seal, unlike a more rigid, or inextensible stabilizer.Silicone may provide an improved “grip” to the patient's skin. Moldingthe main loop is a relatively simple, low waste manufacturing step anddoes not require additional assembly processes (such as stitching astiffener to a foam and fabric laminate). Die cutting a shape thatcannot be readily nested from a sheet may result in wasted material. Inaccordance with a preferred form of the present technology, the rearstrap 85 is relatively straight, and hence can be die cut from a sheetof material with relatively little waste. Hence the preferred form ofseal positioning and stabilising structure is more cost effective.

The main straps 74 r, 74 l may have a width of about 5 mm to about 15mm, for example about 10 mm, in the region configured to engage thecrown of the patient's head and may widen to a width of about 15 mm toabout 25 mm, for example about 20 mm in the region configured to contactthe patient's face in the region of the cheek, for example in the regionaround the strap connector 82. The width of the straps 74 r, 74 l maynarrow between strap connector 82 and the connector 84, for example fromabout 20 mm to about 10 mm, and then increase toward the connector, forexample to about 15 mm to about 25 mm, for example about 20 mm.

A strap connector 82 may be provided in the stiffened region 78. Thestrap connector is configured to receive, for example, a rear strapconfigured to extend around the back of the head of the patient tosecure the seal positioning and stabilizing structure to the patient,and facilitating lengthwise adjustment of the rear strap in one or twopoints. The back strap may be formed of the same material as the mainstraps 74 r, 74 l, for example, silicone, or formed from foam andfabric, such as BREATHOPRENE®. It should be appreciated that the backstrap may be formed of a different material than the main straps 74 r,74 l, such as elastic, or from a combination of materials. It shouldalso be appreciated that the durometer of the main straps 74 r, 74 l maybe varied along its length instead of, or in addition, to varying thethickness of the main straps 74 r, 74 l.

Each main strap 74 r, 74 l includes a patient interface structureconnector 84 that is configured to receive a corresponding connectorformed on the patient interface structure, described below with respectto FIGS. 17 a-17 f. As shown in FIGS. 16 a-16 g, the patient interfacestructure connector 84 may be in the form of a triangular cut out formedin the end of the main strap 74 r, 74 l. It should be appreciated,however, that the patient interface structure connector 84 may comprisea cut out having a different shape than triangular.

3.3.9 Seal Positioning and Stabilizing Structure—Strap Connectors

Silicone is more flexible than standard headgear materials, such asBREATHOPRENE®, and may not perform as desired in standard headgear strapconnectors. For example, silicone has a tendency to slide in theconnector(s) and become loose. As discussed in more detail below, sampleembodiments of seal positioning and stabilizing structure strapconnectors are particularly suitable for use with silicone sealpositioning and stabilizing structure straps, although the sampleembodiments are not limited to silicone seal positioning and stabilizingstructure straps.

3.3.9.1 Ladder Lock Strap Connector

Referring to FIGS. 19 a and 19 b, the straps of the seal positioning andstabilizing structure, for example top straps 40, may be secured by aladder lock connector 86. The ladder lock connector 86 may comprise afirst side member 88 and a second side member 90. A first cross member92 and a second cross member 94 extend between the first side member 88and a second side member 90. A third cross member 96 is spaced from thefirst cross member 92 to define a first strap slot 100. A fourth crossmember 98 is based from the second cross member 94 to define a secondstrap slot 102. A central aperture 104 is defined between the firstcross member 92 and the second cross member 94 to allow threading ofends 40 a of the top straps 40 through the central aperture 104 and overrespective cross members 92, 94 and under respective cross members 96,98, as shown in FIG. 19 b. As shown in FIG. 19 a, third and fourth crossmembers 96, 98 are wider than first and second cross members 92, 94 toincrease the amount of contact between the cross members 96, 98 and theends 40 a of the straps 40. The increased width of the third and fourthcross members 96, 98 thus increases the frictional contact between theladder lock connector 86 and the straps 40 to provide a more securefitting of the seal positioning and stabilizing structure.

As shown in FIG. 19 a, the first and second side members 88, 90 mayinclude textured surfaces 89, 91, respectively, configured to improve auser's grip on the connector 86 to facilitate connection and/oradjustment of the straps 40 with respect to the connector 86. Thetextured surfaces 89, 91 may be, for example, ridges. Additionally, theside members 88, 90 may each include a depression at the texturedsurfaces 89, 91 to receive the user's fingers.

In a variant form, shown in FIGS. 19 c-19 e, ladder lock connector 86may have leaders 96 a and 98 a to ensure that end 40 a of straps 40 arealigned correctly. The ladder lock connector 86 may only be adjustedwhen in the configuration shown in FIG. 19 b. If silicone sealpositioning and stabilizing structure is used, it is unlikely thatladder lock connector 86 will remain aligned as shown in FIG. 19 b dueto the flexibility of silicone (for example, the ladder lock connector86 tends to rotate 90°). To resolve this, leaders 96 a and 98 a may beextended distally from cross members 96 and 98. The leaders 96 a and 98a may be generally rectangular or any other desirable shape. The leaders96 a and 98 a may enclose straps 40 and ends 40 a or may enclose only aportion of straps 40 and ends 40 a. The leaders 96 a and 98 a may beabout 5-30 mm long, for example about 10 mm long, as indicated by L_(L)in FIG. 19 d. The leaders 96 a and 98 a may closely conform to theperimeter formed by straps 40 and ends 40 a, i.e. the outline of thestrap 40 and the strap end 40 a when looped through the connector.Alternatively, as shown in FIG. 19 e the leaders 96 a and 98 a may leaveat least a 1 mm clearance C, for example about 2 mm, as another exampleno more than about 10 mm, around the perimeter formed by straps 40 andends 40 a.

3.3.9.2 Discretely Adjustable Strap Connectors

Referring to FIGS. 20 a and 20 b, a strap connector according to anothersample embodiment comprises a first strap 108 having a first strapconnector 110 formed at an end thereof. A second strap 114 has a secondstrap connector 116 provided at an end thereof. The second strap 114 maycomprise a stud 118 that is insertable into a selected aperture 112formed in the end of the first strap 108. The stud 118 may be generallymushroom shaped in order to lock the first strap 108 in position. Theseal positioning and stabilizing structure may thus be adjusted byselecting the appropriate aperture 112 that provides the mostcomfortable fit for the patient while maintaining an effective sealbetween the patient interface structure and the patient's airways.

Referring to FIGS. 21 a and 21 b, a seal positioning and stabilizingstructure strap connector assembly according to another sampleembodiment comprises a first strap 120 having a stud 124 formed on anend thereof. A guide 122 is provided at the end of the first strap 120.A second strap 126 of the seal positioning and stabilizing structure maycomprise a plurality of apertures or holes 130 that are selectivelyreceived by the stud 124 of the first strap 120. The second strap 126may comprise a ladder lock connector 128 and an end thereof. The secondstrap 126 is threaded through the guide 122 of the first strap 120 andthe stud 124 is inserted into a selected hole or aperture 130 to adjustthe fitting of the seal positioning and stabilizing structure.

Referring to FIGS. 22 a-23 c, a seal positioning and stabilizingstructure strap connector assembly according to another sampleembodiment comprises a first strap 300 having a spring 302 attached onan end thereof. A second strap 301 of the seal positioning andstabilizing structure may comprise a plurality of ridges or corrugations303 that are selectively received by the spring 302 of the first strap300. Spring 302 may comprise a resilient finger 325 that is able to flexwhen corrugations 303 are pulled past the resilient finger 325 whenforce F is applied. As shown in FIG. 22 a, the resilient finger may beprovided on a resiliently cantilevered finger 305 of the spring 302. Asalso shown in FIG. 22 a, the spring 302 may include a cross bar 307 andthe first strap 300 may be connected to the spring 302 by looping an endof the first strap 300 around the cross bar 307. Alternatively, thespring 302 may be integrally formed with the first strap 300 as shown inFIGS. 23 a-23 c.

3.3.9.3 Main Strap Connectors

Referring to FIGS. 24 a-24 p, the left main strap 74 l of the sealpositioning and stabilizing structure comprises a strap connector 82configured to receive one end of a rear strap of the seal positioningand stabilizing structure. The left main strap 74 l also includes apatient interface structure connector 84 l, e.g. a generally triangularcut out, is configured to receive left connector of the patientinterface structure. The left main strap 74 l also includes a pluralityof locking projections 75 and a final locking projection 77. The lockingprojection 75 may have a generally round, oval, or ellipticalconfiguration. The final locking projection 77 is larger than thelocking projections 75 and extends above the locking projection 75, asshown for example in FIG. 24 b, to prevent the seal positioning andstabilizing structure from being completely disassembled.

Referring to FIGS. 24 e-24 h, the right main strap 74 r of the sealpositioning and stabilizing structure comprises a strap connector 82configured to receive the other end of the rear strap. The right mainstrap 74 r also includes a patient interface structure connector 84 r,e.g. cut out, that is configured for connection to a right connector ofthe patient interface structure. A locking connector 79, for example aladder locking connector, is provided at an end of the right main strap74 r to receive the end of the left main strap 74 l. As shown in FIG. 24i, the end of the left main strap 74 l is inserted into the ladderlocking connector 79 in the direction shown by the arrow to connect theleft main strap 74 l to the right main strap 74 r. The end of the leftmain strap 74 l may include a depression 74 d to aid in insertion of theend through the locking connector 79.

As shown in FIG. 24 l, the locking connector 79 includes a lockingprojection 81 that is configured to engage the left main strap 74 lbetween locking projections 75 to maintain the connection between theleft and right main straps 74 l, 74 r. The locking projection 81 islarger than the space between corresponding locking projections 75 toimprove the retention of the main straps 74 l, 74 r. As shown in FIG. 24l, the final locking projection 77 is higher than the locking projection75 to prevent the seal positioning and stabilizing structure from beingcompletely disassembled. It should be appreciated that the main straps74 l, 74 r and the locking projections 75, 77, 81 may be formed ofmaterial that is flexible enough to permit disassembly upon applicationof a sufficient force. The main straps 74 l, 74 r and the lockingprojections 75, 77, 81 may be configured to resist disassembly due toforces such as tube drag or forces normally applied to the sealpositioning and stabilizing structure while wearing, and/or sleepingwith, the mask system. An advantage of molding the main strap connectorsinto the straps is that it simplifies the manufacturing process, and ismore cost-effective, since an additional fastener is not required.

As shown in FIG. 24 l, a slot 83 is provided in the right main strap 74r to permit the end of the left main strap 74 l to flex downwardly asthe locking projection 81 engages the locking projections 75. The slot83 permits the portion of the left main strap 74 l that extends over theslot 83 to be displaced downwardly as the locking projection 81 engagesthe left main strap 74 l between locking projections 75.

Referring to FIG. 24 m, a rear strap 85 may be connected to the mainstraps 74 l, 74 r through the strap connectors 82. Ends 85 e of the rearstrap 85 may be provided with hook or loop type fasteners to engagecorresponding loop or hook fastener material provided on the rest of therear strap 85 to permit adjustment of the length of the rear strap 85extending between the main straps 74 l, 74 r. Although FIGS. 24 m-24 qshow the rear strap 85 as having two adjustable ends 85 e, it should beappreciated that the rear strap 85 may be provided with only oneadjustable end.

The durometer of the left main strap 74 l may be higher in specificareas to provide increased durability, ease of adjustment, andmaintenance of shape. For example, the strap connector 82, the portionsurrounding the cut out 84 l, the locking projections 75 and the finallocking projection 77 may be provided with a higher durometer than theother portions of the left lateral member 74 l. The higher durometer ofthe locking projection 75 and the final locking projection 77 improvethe function of the ladder lock buckle formed by the connection of thelocking projection 75 with the ladder locking connector 79 of the rightmain strap 74 r. The higher durometer provided at the strap connector 82may improve the durability of the seal positioning and stabilizingstructure. The silicone material surrounding the slot of the strapconnector 82 may also be of a thickness sufficient to prevent the slotfrom stretching too much in use. The higher durometer of the portionsurrounding the cut out 84 l may improve connection stability andimprove durability.

Similarly, the right main strap 74 r may have an increased durometer atthe ladder locking connector 79, the strap connector 82 and the portionsurrounding the cut out 84 r to provide benefits similar to thatdiscussed above with respect to the left main strap 74 l.

As shown in FIGS. 24 a-24 q, the left and right main straps 74 l, 74 rare connected at top portion of the patient's head. The rear strap 85does not include a connection such as a buckle or ladder lock connector.This configuration permits the patient to sleep on either side, or onthe patient's back, without the ladder lock connector 79 causing anydiscomfort.

Referring to FIG. 24 r, the left main strap 74 l may include a taperedend 74 t that facilitates insertion of the left main strap 74 l into theconnector 79 of the right main strap 74 r.

A variant of the left and right main straps 74 l, 74 r is shown in FIGS.25 a-25 i. The left main strap 74 l may comprise a first left cut out 84l and a second left cut out 84 a. A bridge or cross bar 84 b is providedbetween the first left cut out 84 l and the second left cut out 84 a.The cross bar 84 b may be provided at a location to engage the leftconnector 322 l of the patient interface structure 6 when the leftconnector 322 l of the patient interface structure 6 is connected to theleft main strap 74 l. The cross bar 84 b may thus act to prevent theleft connector 322 l of the patient interface structure 6 fromdisengaging from the left main strap 74 l when the patient interfacestructure is subject to forces, for example tube drag forces, such asshown in FIGS. 43 a-43 c and FIGS. 44 a-44 c.

The first left cut out 84 l may also comprise a notch 84 c adjacent theend of the left main strap 74 l that allows the left main strap 74 l tobe more flexible when inserting the left connector 322 l through thefirst left cut out 84 l to connect the patient interface structure 6 tothe left main strap 74 l. As shown in FIG. 25 d, which depicts thesurface of the left main strap 74 l configured to engage the face of thepatient, the first left cut out 84 l may comprise sloped walls 84 s thatengage sloped side walls 322 s of the left connector 322 l of thepatient interface structure 6 so that the left connector 322 l and theleft main strap 74 l present a flush surface upon connection asdiscussed in more detail with respect to FIGS. 16-18.

The left main strap 74 l may comprise locking projections, as shown inFIGS. 25 a-25 c, that are configured to engage a locking connector 79,shown in FIGS. 25 e-25 i, to connect the left main strap 74 l and theright main strap 74 r.

Referring to FIGS. 25 e-25 i, the right main strap 74 r may comprise afirst right cut out 84 r and a second right cut out 84 y that areseparated by a bridge or cross bar 84 z. The first right cut out 84 r isconfigured to receive the right connector 322 r of the patient interfacestructure 6 to connect the patient interface structure 6 to the rightmain strap 74 r. The opposite end of the right main strap 74 r comprisesthe locking connector 79 that is configured to engage the lockingprojections 75 of the left main strap 74 l to connect the left and rightmain straps 74 l, 74 r. As shown in FIG. 25 i, the first right cut out84 r may comprise sloped walls 84 s that engage sloped side walls 322 sof the right connector 322 r of the patient interface structure 6 sothat the right connector 322 r and the right main strap 74 r present aflush surface upon connection as discussed in more detail with respectto FIGS. 16-18

Referring to FIGS. 26 a-26 d, according to another variant the left mainstrap 74 l may be provided with locking projections 75, but without afinal locking projection. As shown in FIG. 26 d, the locking projection81 of the ladder locking connector 79 may be generally about the samesize as the locking projections 75 of the left main strap 74 l. Thispermits the connection of the main straps 74 l, 74 r in a comparativelyeasier manner than the connection disclosed in FIGS. 24 a-24 p.

The right and left main straps 74 r, 74 l may be adjustable by a springloaded clip that, when squeezed together, opens up and allows thelateral side members to pass through, but when not squeezed holds thestraps in a locked position. Such a spring loaded clip is similar to adraw cord that is used to allow for adjustment of a cord, for example acord that functions as a bag closure or a cord that adjust the fit of ahat or cap.

Referring to FIG. 26 e, in an alternative embodiment, the right mainstrap 74 r may be provided with a slit or opening that, when relaxed, isclosed, but when squeezed at its furthest edges (as shown by thearrows), opens up and allows the left main strap 74 l to pass throughthe slit or opening. It should be appreciated that the left main strapmay include the slit or opening and the right main strap may be insertedtherein.

The right and left main straps 74 l, 74 r of the main strap loop 74 maybe formed, for example, from silicone. The silicone may be molded tocomprise mushroom shaped studs 74 m on both main straps, or lateral sidemembers, 74 l, 74 r. The studs 74 m, when pushed together, create aninterference fit as shown in FIG. 26 f. The studs 74 m may be any othershape, such as a tree shape, an arrow shape, or a lollipop shape. Thestuds 74 m may also be retrofittable to the lateral side members 74 l,74 r or molded with the lateral side members 74 l, 74 r.

3.3.9.4 Additional Strap Connectors

Hook and loop fastener material, e.g. VELCRO®, may be provided to themain straps 74 r, 74 l, i.e. hook material on one lateral side memberand loop material on the other. The hook and loop fastener material maybe attached to the main straps by, for example, adhesive or overmoldingthe material into the main straps. Alternatively and/or additionally,other adjustment mechanisms, such as magnets, elastic or push clips, maybe overmolded into the lateral side members. A preferred form of patientinterface in accordance with the present technology includes threepoints of lengthwise adjustment: one on the crown of the patient's headfor lengthwise adjustment of the main loop, and one on either side ofthe patient's head (a sub-total of two) generally above the ears forlengthwise adjustment of the rear strap. Some prior art patientinterfaces may require adjustment of ten separate points in order tofind a suitable seating for the headgear, making the process of fittingmore complicated. Preferably the rear strap does not include a buckle atthe rear of the patient's head, as such a buckle may be uncomfortable tolie on.

3.4 Patient Interface Structure and Seal Positioning and StabilizingStructure Connectors 3.4.1 Connectors Extend Toward Flexible Base ofPatient Interface Structure

In use, the patient interface structure 320 may be connected to the mainstrap loop 74 of the seal positioning and stabilizing structure byinserting a connector 322 into the patient interface structure connector(e.g. cut out) 84 of each main strap 74 r, 74 l. As shown, for examplein FIG. 17 c, the connector 322 is wider than the patient interfacestructure extension 323. The connector 322 is also wider than the cutout 84 in the main strap loop 74. The connector 322 is inserted throughthe cut out 84 to connect the patient interface structure 320 to themain strap loop 74, as shown in FIGS. 18 a-18 c. As shown in FIGS. 16 aand 17 a, the cut out 84 and the connector 322 include complementarysurfaces 84 c, 322 c, respectively, that are engaged when the connector322 is connected to the main strap 74 r, 74 l. The connector 322 alsoincludes sloped side walls 322 s (FIG. 17 c) that engage with slopedwalls 84 s (FIG. 16 a) of the cut out 84 when the connector 322 isconnected to the main strap 74 r, 74 l so that the connector 322 and themain strap 74 r, 74 l present a flush surface upon connection, as shownin FIG. 18 b. As shown in FIG. 18 a, the cut out 84 may include inwardlydirected projections 84 p that will engage the end of the connector 322upon connection of the patient interface structure 320 to the main straploop 74 (i.e. the right and left main straps 74 r, 74 l) to provide amore secure attachment of the patient interface structure 320 to themain strap loop 74 of the seal positioning and stabilizing structure.

3.4.2 Connectors Extend Toward Seal of Patient Interface Structure

According to another sample embodiment, shown in FIGS. 18 d-18 f, theconnector 322 may extend from the extension 323 generally in thedirection of the nozzles 328 and away from the flexible base 329, asshown in FIG. 18 d. The connector 84 is placed over the connector 322 sothat when the connector 322 is engaged with the connector 84, theextension 323 is visible, as shown in FIGS. 18 e and 18 f. The assemblymay be secured in the same manner described above with respect to FIGS.18 a-18 c and may provide a more secure connection when the mask systemis in use.

Referring to FIG. 18 g, the left and right connectors 322 l, 322 r,respectively, of the patient interface structure 320 are connected tothe left and right main straps 74 l, 74 r, respectively, of the sealpositioning and stabilizing structure through the left and rightconnectors (e.g. cut outs) 84 l, 84 r, respectively. The geometry of theconnectors 322 l, 322 r matches the geometry of the cut outs 84 l, 84 rto provide an intuitive assembly for the user. The user may get atactile indication that the connectors 322 l, 322 r are properlyinserted into the cut outs 84 l, 84 r and assembled in the connectedposition.

3.4.3 Connectors with Alignment Indicators

Referring to FIG. 18 h, in order to ensure correct alignment of thepatient interface structure 320 into the left main strap 74 l and theright main strap 74 r of the seal positioning and stabilizing structure,the connectors 322 l, 322 r may include indicia 340 which indicate theleft side and the right side. The connectors 322 l, 322 r may alsoinclude a left indicator tab 342 and a right indicator tab 344 to alignthe patient interface structure 320 correctly in the seal positioningand stabilizing structure. As shown in FIG. 18 h, the indicator tabs342, 344 may have different shapes to facilitate alignment of thepatient interface structure 320 in the seal positioning and stabilizingstructure. Although the alignment indicator tabs 342, 344 are shown onthe connectors 322 l, 322 r of the patient interface structure 320, itshould be appreciated that the alignment indicator tabs may be providedon the main straps 74 l, 74 r of the seal positioning and stabilizingstructure, or that the alignment indicator tabs may be provided on boththe connectors of the patient interface structure and the main straps ofthe seal positioning and stabilizing structure.

Referring to FIG. 18 i, the connectors 322 l, 322 r, may include adifferent number of alignment indicator tabs 342, 344 to indicate theproper direction. For example, the left connector 322 l may include oneindicator tab 342 and the right connector 322 r may include twoindicator tabs 344. It should also be appreciated that the position ofthe alignment indicator tabs 342, 344 may be provided in differentplaces to indicate the direction. For example, the left indicator tab342 may be provided on a side of the connector 322 l and the rightindicator tabs 344 may be provided on top of the right seal positioningand stabilizing structure connector 322 r. It should also be appreciatedthat the indicia 340 may also be provided, for example, on the alignmentindicator tabs 342, 344.

As shown in FIG. 18 j, according to another sample embodiment, thepatient interface structure 320 may be aligned properly with the sealpositioning and stabilizing structure by providing the left sealpositioning and stabilizing structure connector 322 l with a differentshape than the right seal positioning and stabilizing structureconnector 322 r. As shown in FIG. 18 k, the left cut out 84 l has ashape corresponding to the left connector 322 l and the right cut out 84r has a different shape corresponding to the differently shaped rightconnector 322 r. The differently shaped connectors and cut outs ensuresproper alignment of the patient interface structure 320 with the sealpositioning and stabilizing structure in the assembled position shown inFIG. 18 l.

Referring to FIGS. 18 m-18 p, the seal positioning and stabilizingstructure connectors 322 l, 322 r may face upwards towards the pillows328 of the patient interface structure 320. This configuration may beprovided to avoid accidental disassembly of the patient interfacestructure 320 from the seal positioning and stabilizing structure. Asshown in FIGS. 18 o and 18 p, the connectors 322 l, 322 r may includestepped portions 322 s that engage with stepped portions 84 s of thelateral members 74 l, 74 r so that the connection between the patientinterface structure and the seal positioning and stabilizing structurecannot be accidentally disassembled by pulling the seal positioning andstabilizing structure up from the tabs. The seal positioning andstabilizing structure must be pushed inwards towards the nasal pillows328 to disengage the stepped portions 322 s and then pulled upwards inorder to disassemble the connection of the patient interface structureand the lateral members of the seal positioning and stabilizingstructure.

As shown in FIG. 18 q, the cut out 84 l may include a notch, or cut out337, to improve bending of the material of the left strap loop 74 l tofacilitate connection and disconnection of the connector 322 l from thecut out 84 l. It should be appreciated that the cut out 337 may bealternatively, or additionally, provided to the right strap loop 74 r.

As discussed above, the seal positioning and stabilizing structure isnot connected to any “hard” parts, for example a rigid polycarbonateshell or frame such as used in prior art mask assemblies, although itshould be appreciated that patient interface structure may be connectedto a hard part, such as a rigid frame or shell, that is in turnconnected to the seal positioning and stabilizing structure.

3.5 Decoupling Arrangements 3.5.1 Hinge or Universal Joint

Referring again to FIGS. 7 a-7 d, the air delivery tube 16 may beconnected to the patient interface structure 32 by a decouplingarrangement 44. The decoupling arrangement 44 may comprise, for example,a hinge mechanism. The decoupling arrangement 44 may comprises aconnection between the tube 16 and the patient interface structure 32that provides more than one axis of rotation. Referring to FIG. 7 d, theflexible base 6 of the patient interface structure may be divided intothe lower portion 6 l and the top portion 6 t by a hinge or universaljoint 440 to further isolate the tube drag forces from the forces of theseal positioning and stabilizing structure.

3.5.2 Flexible Elbow

Referring to FIG. 5 b, a flexible elbow 409 may comprise a flexible“skeleton” 411 comprising a plurality of rigid hoops, or rings, 405connected by a flexible lattice 406. An overmold 408 formed of, forexample, silicone is provided over the skeleton 402 to form the flexibleelbow. The rings 405 provide a minimal support structure that ensuresthat the elbow 400 does not collapse, but maintains the flexibility ofthe elbow 409 and prevent occluding.

3.5.3 Diaphragm

In another form, the decoupling arrangement 44 may comprise a diaphragmbetween an elbow connected to the tube 16 and the patient interfacestructure 32, or the flexible base 6 of the patient interface structure32. The diaphragm may be a thinned section with a flat cross section.Alternatively, the cross section of the diaphragm may be wave-shaped,zig-zagged, or any other desired shape.

Referring to FIGS. 5 c and 5 d, the elbow 400 may have a rigid collar410 that is supported by a diaphragm 414 that is provided between thecollar 410 and a rigid frame 412, or a relatively more rigid section, ofthe patient interface structure. The diaphragm 414 may be flat, or havea wave-shaped configuration, or a concertina-type configuration. Thediaphragm 414 may be formed of, for example, silicone.

3.5.4 Linking Element

Referring to FIGS. 8 l and 8 m, seal positioning and stabilizingstructure is used to stabilize a mask system on the face of the patient.However, the stabilization can be offset by air delivery tube dragforces. Typically, the frame of a mask system will direct forces fromthe headgear and the air delivery tube in such a way that the mask isstill able to seal. In the sample embodiments, seal positioning andstabilizing structure is connected to the patient interface structure,not to the frame. The patient interface structure thus needs to directthe forces, i.e. seal positioning and stabilizing structure and airdelivery tube drag forces. As shown in FIG. 8 l, a patient interfacestructure according to an embodiment , for example the embodiment shownin FIG. 4, the air delivery tube drag force acts on the patientinterface structure at the top portion 6 t, which may cause the nasalpillows to be pulled away from the patient's nares. The patientinterface structure shown in FIG. 8 l may not be able to direct sealpositioning and stabilizing structure and air delivery tube forces whilemaintaining a seal.

As shown in FIG. 8 m, the provision of a linking element(s) to the topportion to isolate the seal positioning and stabilizing structure forcesand direct the seal positioning and stabilizing structure and tube dragforces appropriately. The lines of tension force are directed throughthe top portion 6 t of the patient interface structure 32, therebyallowing the base portion 6 of the patient interface structure 32 todecouple tube drag forces. The linking element facilitates decoupling ofthe top portion 6 t with respect to the lower portion 6 l by drawing thetension lines of force through the top portion of the patient interfacestructure 32 and isolates such forces from the base portion of thepatient interface structure. The tension linking element isolates thetube drag force at the base portion 6 of the patient interfacestructure, for example the lower portion 6 l, which may include, or beconfigured as, a gusset. By distributing the forces to the lower portion6 l, the patient interface structure is stabilized in the patient'snares in use.

3.5.5.1 Sealing Ring—First Embodiment

Referring to FIGS. 9 a and 9 b, a respiratory mask system according toanother sample embodiment includes a patient interface structure 32.FIG. 9 a illustrates a cross section through the flexible base 6 of thepatient interface structure 32 in between the nasal pillows 4. It shouldbe appreciated that the patient interface structure may be, for example,a nasal cushion or a full face cushion. It should also be appreciatedthat the patient interface structure may be formed as a compactoro-nasal interface in a manner similar to that disclosed in U.S. PatentApplication Publication 2007/0144525 A1, the entire contents of whichare incorporated herein by reference. For example, the compact oro-nasalinterface may be modified to include connectors for the seal positioningand stabilizing structure straps provided on the patient interfacestructure or the nozzles. The patient interface structure 32 may beconnected to an elbow 60 which may be connected to an air delivery tube.The elbow 60 may include a vent 62 to permit the exhaust of thepatient's exhalation.

The patient interface structure 32 may be swivelably connected to theelbow 60 by a swivel seal ring 64. As shown in FIGS. 9 a and 9 b, thepatient interface structure 32 may include a flexible base 6 having anaperture 46 for the introduction of the flow of breathable gas. Theaperture 46 may be surrounded by a flange 48 which extends radiallyinwardly around the aperture 46. The flange may include a chamfer 45extending around the circumference of the flange 48. As shown in FIG. 9b, the flange 48 of the patient interface structure 32 is received in aspace between a first flange 64 a and a second flange 64 b of the swivelseal ring 64 to form a secure seal assembly. The chamfer 45 allows theflange 48 of the patient interface structure 32 to be inserted andremoved from the space more easily. The swivel seal ring 64 ismaintained on an end of the elbow 60 between a first flange 60 a and asecond flange 60 b of the elbow 60. A radial seal is formed at thecontact between the second flange 64 b of the swivel seal ring 64 andthe second flange 60 b of the elbow 60. The connection of the flange 48of the patient interface structure 32 to the swivel seal ring 64 permitsthe patient interface structure to swivel or rotate with respect to theelbow. The swivel seal ring 64 thus assists decoupling tube drag forcesfrom the seal. The embodiment of FIGS. 9 a and 9 b thus replaces thepatient interface structure-to-frame connection mechanism of the priorart with a patient interface structure-to-elbow connection.

3.5.5.2 Sealing Ring—Second Embodiment

In a variant shown in FIGS. 17 h and 17 i, the flange 326 of the patientinterface structure may have a varied thickness T3. For example, theflange 326 may be formed as a tapered flange 331 so that it is easier toinsert into the swivel ring 64. The taper may be an angle α in the rangeof about 5°-50°, for example about 15°. The surface of the taperedflange 331 may be polished to improve sealing. Alternatively, thesurface of the tapered flange 331 may be textured for easier sliding ofthe swivel ring 64.

Referring to FIG. 17 j, the patient interface structure 320 is connectedto a swivel elbow assembly 17 having a hose 16 connected thereto by asealing ring 64 that is insertable into the aperture 324 of the patientinterface structure 320 for engagement with the flange 326. As shown inFIG. 17 k, the flange 326 comprises a tapered flange 331 that isconfigured to be inserted into a groove or slot defined by the sealingring 64.

The tapered flange 331 may be assembled to the sealing ring 64 by simplyinserting the sealing ring 64 into the aperture 324 of the patientinterface structure 320, or by inserting the tapered flange 331 of thepatient interface structure 320 over the sealing ring 64, or by acombination of these actions.

The tapered flange 331 and sealing ring 64 provide a small and simpleconnection of the patient interface structure 320 to the swivel elbowassembly 17 that does not affect the patient interface structureperformance. The sealing ring 64 also allows the swivel elbow assembly17 to be assembled to the patient interface structure 320 in such a wayas not to compromise the retention of the swivel elbow assembly 17 withthe patient interface structure 320.

3.5.5.3 Sealing Ring—Third Embodiment

Referring to FIG. 17 l, the aperture 324 of the patient interfacestructure 320 may include a threaded portion 324 t and the sealing ring64 may comprise a corresponding threaded portion 64 t that allows thesealing ring 64 to be threadably fastened to the patient interfacestructure 320.

3.5.5.4 Sealing Ring—Fourth Embodiment

As shown in FIG. 17 m, according to another variant, the aperture 324 ofthe patient interface structure 320 may have a plurality of holdingportions 324 h and a corresponding number of releasing portions, oropenings, 324 r. The sealing ring 64 comprises a corresponding number ofprojections 64 p that are received in the releasing portions 324 r androtated into engagement with the holding portions 324 h to form abayonet type connection between the sealing ring 64 and the patientinterface structure 320.

3.5.5.5 Sealing Ring—Fifth Embodiment

Referring to FIGS. 17 n and 17 o, a swivel seal ring 64 may have anasymmetrical configuration including a first flange 64 a that has alarger diameter than a second flange 64 b. A gap, or space, 64 g isprovided between the first and second flanges 64 a, 64 b to receive theflange of the patient interface structure. The second flange 64 bcomprises a sloped surface 64 s that facilitates insertion of thesealing ring 64 into the aperture of the patient interface structure.The second flange 64 b is configured to contact an edge 60 e of theelbow 60 to form a radial seal.

3.5.6 Trampoline

Referring to FIGS. 27 a and 27 b, the stalks or neck portions 10 of thenasal pillows 4 may be connected to the top portion 6 t of the baseportion 6 of the patient interface structure and comprise thinned, orreduced thickness, portions 7. The thinned portions 7 allow the pillows4 to easily spring, or trampoline, and therefore adjust to suit the alarangle of the patient more readily.

In a variant shown in FIGS. 18 p and 18 s, the top portion 6 t of theflexible base 6 may include thinned portions, or trampolines, 335between the stalks, or neck portions, 332 of the nasal pillows 328 andthe linking element 47.

3.5.7 Flexible Base

Referring to FIGS. 43 a-43 c, the flexible base 6 of the patientinterface structure is configured to conform to wrap around theunderside of the nose of the patient in use when under tension. Theflexible base 6 can assist in decoupling the seal, e.g. the nasalpillows 328, from tube drag forces on the tube 16, which may beconnected to the patient interface structure by the elbow 17. As shownin FIG. 43 a, essentially no tube drag force is exerted on the patientinterface structure. The nasal pillows 328 are both in sealingengagement with the patient's nare. Referring to FIG. 43 b, a force maybe exerted on the tube 16 on the right side of the patient's face. Theflexible base 6 compresses on the right side of the patient's face whilepermitting the nasal pillow 328 on the left side of the patient's faceto remain in sealing engagement with the patient's nare. As shown inFIG. 43 b, stalk, or neck portion, 332 of the left nasal cushion 328 isless compressed than the stalk 332 of the right nasal cushion 328. Itshould be appreciated that the compressibility of the stalks 332 and,for example, thinned regions or trampolines around the stalks 332 mayfurther assist in decoupling forces, for example tube drag, exerted onthe tube or patient interface structure from the seal. As shown in FIG.43 c, in the case where tube drag is exerted to the left side of thepatient's face, the left side of the flexible base 6 is compressed, asis the stalk of the left nasal pillow 328. The right nasal cushion 328remains in sealing engagement with the patient's right nare. The stalk332 of the right nasal cushion 328 may articulate to assist inmaintaining the right nasal cushion 328 in sealing engagement.

Referring to FIGS. 44 a-44 c, the flexible base 6 may also assist inforces, e.g. tube drag, applied in an up and down direction. As shown inFIGS. 44 a, in a case where no external forces are applied, the nasalcushions 328 are in sealing engagement with the nares of the patient. Asshown in FIG. 44 b, if an upward force is applied to the patientinterface structure, the flexible base 6 assists in decoupling the forceso the nasal cushions 328 remain in sealing engagement. As shown in FIG.44 c, if a downward force is applied to the patient interface structure,the flexible base 6 assists in decoupling the force so that the nasalcushions 328 remain in sealing engagement with the nares. The stalks 332may also compress, in the case of the upward force shown in FIG. 44 b,or expand, in the case of the downward force shown in FIG. 44 c, toassist in decoupling the force(s). It should also be appreciated thatthinned regions, or trampolines, provided in the patient interfacestructure around the stalks and/or at the base of the frusto-conicalsealing surface or zone may assist in decoupling the force(s).

Although FIGS. 43 a-43 c depict decoupling of force(s) in the left toright directions, and FIGS. 44 a-44 c depict decoupling of force(s) inthe up and down directions, the flexible base may assist in decouplingforces in other directions, e.g. directions that are combinations ofleft to right, or up to down, or directions that are toward and awayfrom the face of the patient.

As described above, the plenum of the base of the patient interfacestructure is semi-rigid, or flexible, so that the plenum will bend orflex when force, such as tube drag, is applied to the patient interfacestructure. The plenum is semi-rigid, or flexible, enough to maintain theventing of the patient interface structure, for example through a ventprovided in an elbow connected to the patient interface structure. Inother words, the plenum is semi-rigid, or flexible, enough to preventthe plenum from collapsing on itself and preventing venting of thepatient interface structure.

3.5.8 Flexible Straps

As discussed above with respect to FIGS. 43 a-44 c, the straps, e.g. theflexible main straps 74 r, 74 l, may stretch to assist in decouplingforce(s) applied to the patient interface structure, for example tubedrag. The straps may also bend or flex to assist in decoupling force(s)applied to the patient interface structure. For example, the mainstrap(s) 74 r, 74 l may bend or flex, in and/or out of a plane definedby the strap(s) to assist in decoupling the force. As another example,the forked region of the strap(s) 74 r, 74 l defined by the connector 84may bend, flex, and/or stretch in response to the applied force(s).

Although the various sample embodiments have been described in relationto a seal positioning and stabilizing structure generally including sidestraps, a top strap and a rear strap, and a main strap loop and a rearstrap loop, it should be appreciated that other seal positioning andstabilizing structures may be used. For example, the seal positioningand stabilizing structure may include straps that are routed around andengage the ears of the patient. The seal positioning and stabilizingstructure may comprise elastic and/or inelastic straps. The sealpositioning and stabilizing structure may also be provided in varioussizes. The seal positioning and stabilizing structure may be formed fromsilicone. For example, the seal positioning and stabilizing structuremay be molded from silicone as one single piece. However, it should beappreciated that the seal positioning and stabilizing structure may bemolded in several pieces, for example two, three or six pieces.Alternatively, silicones of varying durometer (i.e. hardness) may beco-molded. The silicone may also vary in width and depth (thickness)throughout the seal positioning and stabilizing structure, as shown forexample in FIGS. 16 a-16 g, to strengthen the seal positioning andstabilizing structure in areas where force concentrations are higher,e.g. the cheek region. The straps may also have an anti-sweatingfeature. For example, the side of the straps configured to contact thepatient's face may be textured to minimize or prevent sweating.

It should also be appreciated that the seal positioning and stabilizingstructure and patient interface structure may be formed as one piecewith interchangeable nasal pillows, for example as disclosed inAustralian Application 2004308536, filed Dec. 24, 2004, the entirecontents of which are incorporated herein by reference.

It should also be appreciated that the patient interface systems maycomprise a nasal clip, instead of a seal positioning and stabilizingstructure, to hold the patient interface structure in position on thepatient's face.

The patient interface structures have been described above in relationto the illustrated sample embodiments as being formed of, for example,silicone. It should be appreciated that the patient interface structuresmay be formed of, for example, a foam material, such as disclosed inInternational Applications PCT/AU2007/001051, filed Jul. 30, 2007, andPCT/AU2007/001052, filed Jul. 27, 2007, and Australian ProvisionalApplication 2007906102, filed Nov. 6, 2007, the entire contents of allthree applications being incorporated herein by reference. It shouldalso be appreciated that the patient interface structure may comprise agel.

3.6 Elbow

Referring to FIGS. 49-51, an elbow 17 according to a sample embodimentcomprises a first end configured for connection to a patient interfacestructure, for example by use of a sealing ring. The elbow 17 includes asecond end 174 configured for connection to a hose or tube or conduitthat delivers a flow of breathable gas.

The elbow 17 comprises a plurality of vent holes 171 that are formed ina portion of an outer circumferential wall of the elbow 17. As shown inFIGS. 49 and 51, the portion of the outer circumferential wall thatincludes the vent holes 171 comprises a plurality of perpendicular steps172 formed in the outer circumferential wall. As shown in FIG. 51, eachvent hole 171 is perpendicular to a respective step 172. As shown inFIGS. 49 and 50, each step 172 may have a plurality of vent holes 171provided perpendicular to the step 172.

Referring to FIG. 52, an apparatus and method for forming the elbow 17includes inserting a plurality of pins 175 (only one shown) into theouter circumferential wall of the elbow 17 during the molding of theelbow. A plurality of blank offs 177 (only one shown) corresponding tothe plurality of steps 172 are pressed against the outer circumferentialwall of the elbow to form the steps 172. The respective pins 175 contactthe respective blank offs 177 during molding to form each vent hole 171perpendicular to the respective step 172. It should be appreciated thatthe plurality of blank offs 177 may be provided on a single tool orportion of the mold and the plurality of pins 175 may be provided on asingle tool or portion of the mold that are configured to be movableinto and out of engagement with each other during molding of the elbow.

As shown in FIG. 52, each pin 175 includes a front surface 176 that isconfigured to contact a surface 178 of the blank off 177. Whencontacting, the surfaces 176, 178 are parallel to one another. Thiscontrasts with prior art pins, such as the pin 179 shown in FIG. 53, inwhich the front surface 180 is provided at an angle 181 toperpendicular. The prior art pins 179 tend to cause flashing duringmolding of the elbow as the material may tend to leak along the partingline of the mold and the pin 179 into the space between the angledsurface 180 and perpendicular. The formation of flash around the ventholes 171 may cause some or all of the vent holes to be either partiallyor totally blocked, resulting in reduced venting from the elbow 17. Byproviding the pin 175 having the front surface 176 that matches thesurface 178 of the blank off 177 in the embodiment shown in FIGS. 49-52,flash is prevented by the engagement of the surfaces 176, 178. Byforming the vent holes 171 perpendicular to the steps 172, the elbow maybe designed in a larger range of elbow angles as the vent holes 171 areperpendicular to the steps 172 and vent away from the outercircumferential wall at any elbow angle.

As shown in FIGS. 49 and 50, the elbow comprises nine perpendicularsteps. It should be appreciated however that another number of steps maybe provided. As also shown in FIGS. 49 and 50, the vent holes 171 ineach step 172 may be offset from the vent holes 171 the preceding and/orfollowing step 172, i.e. the center of each vent hole 171 in each stepis displaced from the center of the adjacent vent hole or holes 171 inthe preceding and/or following step 172. It should be appreciated thatthe vent holes 171 may not be displaced from the vent holes in thepreceding and/or following step. Although the elbow is shown comprisingforty three vent holes, it should be appreciated that the elbow mayinclude another number of vent holes.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope. Also, the various embodiments described above may be implementedin conjunction with other embodiments, e.g., aspects of one embodimentmay be combined with aspects of another embodiment to realize yet otherembodiments. Further, each independent feature or component of any givenassembly may constitute an additional embodiment. Furthermore, eachindividual component of any given assembly, one or more portions of anindividual component of any given assembly, and various combinations ofcomponents from one or more embodiments may include one or moreornamental design features. In addition, while the invention hasparticular application to patients who suffer from OSA, it is to beappreciated that patients who suffer from other illnesses (e.g.,congestive heart failure, diabetes, morbid obesity, stroke, bariatricsurgery, etc.) can derive benefit from the above teachings. Moreover,the above teachings have applicability with patients and non-patientsalike in non-medical applications.

1. A headgear for positioning a patient interface structure fordelivering a pressurized flow of breathable gas to the airways of apatient, comprising: at least one flexible strap loop which isattachable to the patient interface structure by a forked region of theat least one strap loop that is mountable on the patient interfacestructure, wherein the at least one strap loop positions the patientinterface structure on the face of the patient, the forked regionincludes two forks adapted to be attached to an upper and lower portionon the patient interface structure, the two forks are connected by abridge so that the forked region is divided into a first region and asecond region, and the first region is mountable on the patientinterface structure.
 2. A headgear according to claim 1, whereindifferential lengths of the two forks apply differential force vectorsonto the patient interface structure to hold it in position on the face.3. A headgear according to claim 1, wherein the at least one strap loopcomprises a first strap loop and a second strap loop, wherein the secondstrap loop engages the first strap loop.
 4. A headgear according toclaim 1, wherein the at least one strap loop is molded.
 5. A headgearaccording to claim 1, wherein the at least one strap loop is elastic. 6.A headgear according to claim 1, wherein the at least one strap loop ismade of a polymer.
 7. A headgear according to claim 1, wherein thebridge is configured to engage the patient interface structure when thefirst region is mounted on the patient interface structure.
 8. Aheadgear according to claim 1, wherein the first region comprises slopedwalls configured to engage sloped surfaces of the patient interfacestructure.
 9. A headgear according to claim 1, wherein the at least onestrap loop comprises a plurality of locking projections on an endopposite the forked region and the second strap loop comprises a lockingconnector configured to receive the opposite end of the first strap loopand engage at least one of the locking projections to connect the firststrap loop to the second strap loop.
 10. A headgear according to claim9, wherein the plurality of locking projections comprises a finallocking projection having a different shape than the other lockingprojections.
 11. An elbow for a patient interface system for deliveringa flow of breathable gas to a patient, the elbow comprising: a firstportion having a first end configured to be connected to the patientinterface system; and a second portion having a second end configured tobe connected to a tube that delivers the flow of breathable gas, whereinan outer circumferential wall comprises a plurality of perpendicularsteps formed therein and a plurality of vent holes are providedperpendicular to the plurality of perpendicular steps.
 12. An elbowaccording to claim 11, wherein the second portion of the elbow is at anangle to the first portion that is greater than about 90°.
 13. An elbowaccording to claim 11, wherein the vent holes in each step are displacedfrom the vent holes in a following and/or preceding step.
 14. An elbowaccording to claim 11, wherein the elbow comprises nine steps.
 15. Anelbow according to claim 14, wherein the elbow comprises forty threevent holes.
 16. A method of manufacturing an elbow for a patientinterface system for delivering a flow of breathable gas, the elbowcomprising a first portion having a first end configured to be connectedto the patient interface system and a second portion having a second endconfigured to be connected to a tube that delivers the flow ofbreathable gas, the method comprising: forming a plurality ofperpendicular steps in an outer circumferential wall of the secondportion; and forming a plurality of vent holes perpendicular to theplurality of perpendicular steps.
 17. A method according to claim 16,wherein forming the plurality of perpendicular steps comprises pressinga plurality of blank offs against the circumferential wall of the secondportion from a first side during molding of the elbow; and forming theplurality of vent holes comprises inserting a plurality of pins from asecond side opposite the first side into the circumferential wall duringmolding of the elbow.
 18. A method according to claim 17, furthercomprising: contacting a perpendicular surface of each blank off againstperpendicular surfaces of the plurality of pins to prevent flashingaround the vent holes.
 19. A method according to claim 16, whereinforming the plurality of perpendicular steps comprises forming ninesteps.
 20. A method according to claim 16, wherein forming the pluralityof vent holes comprises forming forty three vent holes.